PUBLICATIONS

2011

Abstract:

A small amount of catalyst, such as Ti, was found to greatly improve the kinetics of hydrogen reactions in the prototypical hydrogen storage compound sodium alanate (NaAlH(4)). We propose a near-surface alloying mechanism for the rehydrogenation cycle based on a detailed analysis of available experimental data as well as first-principles calculations. The calculated results indicate that the catalyst remains at subsurface sites near the Al surface, reducing the dissociation energy barrier of H(2). The binding between Ti and Al modifies the surface charge distribution, which facilitates hydrogen adsorption and enhances hydrogen mobility on the surface.

Notes:

ISI Document Delivery No.: 761HCTimes Cited: 0Cited Reference Count: 34Cited References: Ivancic TM, 2010, J PHYS CHEM LETT, V1, P2412 Kopczyk M, 2010, SURF SCI, V604, P988 CHEN JC, 2009, CELL, V113, P11027 Stumpf R, 2008, PHYS REV B, V77, DOI 10.1103/PhysRevB.77.235413 Gunaydin H, 2008, P NATL ACAD SCI USA, V105, P3673, DOI 10.1073/pnas.0709224105 Borgschulte A, 2008, PHYS CHEM CHEM PHYS, V10, P4045, DOI 10.1039/b803147a JENSEN C, 2008, SOLID STATE HYDROGEN, DOI 10.1533/9781845694944.4.381 Graetz J, 2007, J PHYS CHEM C, V111, P19148, DOI 10.1021/jp076804j Du AJ, 2007, CHEM PHYS LETT, V450, P80, DOI 10.1016/j.cplett.2007.09.090 Lohstroh W, 2007, PHYS REV B, V75, DOI 10.1103/PhysRevB.75.184106 Balde CP, 2007, J PHYS CHEM C, V111, P2797, DOI 10.1021/jp064765q Chaudhuri S, 2006, J AM CHEM SOC, V128, P11404, DOI 10.1021/ja060437s Fu QJ, 2006, J PHYS CHEM B, V110, P711, DOI 10.1021/jp055238u Spisak D, 2005, SURF SCI, V582, P69, DOI 10.1016/j.susc.2005.03.005 Chaudhuri S, 2005, J PHYS CHEM B, V109, P6952, DOI 10.1021/jp050558z Lovvik OM, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.054103 Luo WF, 2004, J ALLOY COMPD, V385, P224, DOI 10.1016/j.jallcom.2004.05.004 Graetz J, 2004, APPL PHYS LETT, V85, P500, DOI 10.1063/1.1773614 Bogdanovic B, 2002, MRS BULL, V27, P712, DOI 10.1557/mrs2002.227 Lucadamo G, 2002, J APPL PHYS, V91, P9575, DOI 10.1063/1.1477257 Bogdanovic B, 2000, J ALLOY COMPD, V302, P36, DOI 10.1016/S0925-8388(99)00663-5 Gross KJ, 2000, J ALLOY COMPD, V297, P270, DOI 10.1016/S0925-8388(99)00598-8 Go EP, 1999, SURF SCI, V437, P377, DOI 10.1016/S0039-6028(99)00725-6 Stumpf R, 1997, PHYS REV LETT, V78, P4454, DOI 10.1103/PhysRevLett.78.4454 Bogdanovic B, 1997, J ALLOY COMPD, V253, P1, DOI 10.1016/S0925-8388(96)03049-6 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 Kim SK, 1996, J PHYS-CONDENS MAT, V8, P25, DOI 10.1088/0953-8984/8/1/005 GUNDERSEN K, 1994, SURF SCI, V304, P131, DOI 10.1016/0039-6028(94)90759-5 PERDEW JP, 1992, PHYS REV B, V46, P6671, DOI 10.1103/PhysRevB.46.6671 HARA M, 1991, SURF SCI, V242, P459, DOI 10.1016/0039-6028(91)90309-G VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 MAMULA M, 1967, COLLECT CZECH CHEM C, V32, P884 FINHOLT AE, 1955, J INORG NUCL CHEM, V1, P317, DOI 10.1016/0022-1902(55)80038-3 WIBERG E, 1951, Z NATURFORSCH B, V6, P392Wang, Yan Zhang, Feng Stumpf, R. Lin, Pei Chou, M. Y.Department of Energy[DE-FG02-05ER46229]; Office of Science of the US Department of Energy[DE-AC02-05CH11231]This work is supported by the Department of Energy under Grant No. DE-FG02-05ER46229. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

The surface states of ABC-stacked few-layer graphene ( FLG) are studied based on density-functional theory. These states form flat bands near the Fermi level, with the k-space range increasing with the layer number. Based on a tight-binding model, the characteristics of these surface states and their evolution with respect to the number of layers are examined. The infrared optical conductivity is then calculated within the single-particle excitation picture. We show that the surface states introduce unique peaks at around 0.3 eV in the optical conductivity spectra of ABC-stacked FLG when the polarization is parallel to the sheets, in good agreement with recent experimental measurement. Furthermore, as the layer number increases, the absorption amplitude is greatly enhanced and the peak position redshifts, which provides a feasible way to identify the number of layers for ABC-stacked FLG using optical conductivity measurements.

Notes:

ISI Document Delivery No.: 781LZTimes Cited: 1Cited Reference Count: 41Cited References: Lui CH, 2011, NANO LETT, V11, P164, DOI 10.1021/nl1032827 Zhang F, 2010, PHYS REV B, V82 Mak KF, 2010, PHYS REV LETT, V104 Norimatsu W, 2010, PHYS REV B, V81 Yang L, 2010, PHYS REV B, V81 Koshino M, 2010, PHYS REV B, V81 Yang L, 2009, PHYS REV LETT, V103 Koshino M, 2009, PHYS REV B, V80 Min H, 2009, PHYS REV LETT, V103 Mak KF, 2009, PHYS REV LETT, V102 Zhang YB, 2009, NATURE, V459, P820 Li ZQ, 2009, PHYS REV LETT, V102 Castro Neto AH, 2009, REV MOD PHYS, V81, P109 Stauber T, 2008, PHYS REV B, V78, DOI 10.1103/PhysRevB.78.085432 Li ZQ, 2008, NAT PHYS, V4, P532, DOI 10.1038/nphys989 Wang F, 2008, SCIENCE, V320, P206, DOI 10.1126/science.1152793 Chen JH, 2008, NAT NANOTECHNOL, V3, P206, DOI 10.1038/nnano.2008.58 Oostinga JB, 2008, NAT MATER, V7, P151, DOI 10.1038/nmat2082 MIN H, 2008, SUPPL PROG THEOR PHY, V176, P227 Casiraghi C, 2007, NANO LETT, V7, P2711, DOI 10.1021/nl071168m Jiang Z, 2007, PHYS REV LETT, V98 Yan J, 2007, PHYS REV LETT, V98 Aoki M, 2007, SOLID STATE COMMUN, V142, P123, DOI 10.1016/j.ssc.2007.02.013 Manes JL, 2007, PHYS REV B, V75, DOI 10.1103/PhysRevB.75.155424 Geim AK, 2007, NAT MATER, V6, P183, DOI 10.1038/nmat1849 Lu CL, 2006, APPL PHYS LETT, V89, DOI 10.1063/1.2396898 Ohta T, 2006, SCIENCE, V313, P951, DOI 10.1126/science.1130681 Latil S, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.036803 Guinea F, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.245426 Lu CL, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.144427 McCann E, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.086805 Gajdos M, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.045112 Novoselov KS, 2005, NATURE, V438, P197, DOI 10.1038/nature04233 Zhang YB, 2005, NATURE, V438, P201, DOI 10.1038/nature04235 Berger C, 2004, J PHYS CHEM B, V108, P19912, DOI 10.1021/jp040650f Novoselov KS, 2004, SCIENCE, V306, P666, DOI 10.1126/science.1102896 KRESSE G, 1993, PHYS REV B, V47, P558, DOI 10.1103/PhysRevB.47.558 TSUJI M, 1960, REV MOD PHYS, V32, P425, DOI 10.1103/RevModPhys.32.425 Lipson H, 1942, PROC R SOC LON SER-A, V181, P0101, DOI 10.1098/rspa.1942.0063 WANG ZF, ARXIVCONDMAT0703422V YAN JA, UNPUBYan, Jia-An Ruan, W. Y. Chou, M. Y.US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DEFG02-97ER45632]J.-A.Y. thanks Dr. X. Wang for useful discussions. We acknowledge the support by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DEFG02-97ER45632. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC).AMER PHYSICAL SOCCOLLEGE PK

Abstract:

We have performed first-principles calculations to study the lattice vibrational modes and their Raman activities in silicon nanowires (SiNWs). Two types of characteristic vibrational modes are examined: high-frequency optical modes and low-frequency confined modes. Their frequencies have opposite size dependence with a red shift for the optical modes and a blue shift for the confined modes as the diameter of SiNWs decreases. In addition, our calculations show that these vibrational modes can be detected by Raman scattering measurements, providing an efficient way to estimate the size of SiNWs.

Notes:

ISI Document Delivery No.: 793UMTimes Cited: 0Cited Reference Count: 37Cited References: Khoo KH, 2010, PHYS REV LETT, V105 Bourgeois E, 2010, PHYS REV B, V81 Murphy-Armando F, 2010, NANO LETT, V10, P869 Rurali R, 2010, REV MOD PHYS, V82, P427 Chen X, 2009, J PHYS CHEM C, V113, P14001 Lange H, 2008, NANO LETT, V8, P4614, DOI 10.1021/nl803134t Vo TTM, 2008, NANO LETT, V8, P1111, DOI 10.1021/nl073231d Boukai AI, 2008, NATURE, V451, P168, DOI 10.1038/nature06458 Hochbaum AI, 2008, NATURE, V451, P163, DOI 10.1038/nature06381 Zhang Y, 2007, J APPL PHYS, V102, DOI 10.1063/1.2811862 Wang J, 2007, APPL PHYS LETT, V90, DOI 10.1063/1.2748342 Nobile C, 2007, NANO LETT, V7, P476, DOI 10.1021/nl062818+ Adu KW, 2005, NANO LETT, V5, P409, DOI 10.1021/nl0486259 Thonhauser T, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.081307 BARONI S, 2005, QUANTUM ESPRESSO OPE Thonhauser T, 2004, PHYS REV B, V69, DOI 10.1103/PhysRevB.69.075213 Li DY, 2003, APPL PHYS LETT, V83, P2934, DOI 10.1063/1.1616981 Liu HL, 2001, CHEM PHYS LETT, V345, P245, DOI 10.1016/S0009-2614(01)00858-2 Cui Y, 2001, SCIENCE, V291, P851, DOI 10.1126/science.291.5505.851 Duan XF, 2001, NATURE, V409, P66, DOI 10.1038/35051047 Duesberg GS, 2000, PHYS REV LETT, V85, P5436, DOI 10.1103/PhysRevLett.85.5436 Shi WS, 2000, J AM CERAM SOC, V83, P3228 Jorio A, 2000, PHYS REV LETT, V85, P2617, DOI 10.1103/PhysRevLett.85.2617 Wang RP, 2000, PHYS REV B, V61, P16827, DOI 10.1103/PhysRevB.61.16827 Holmes JD, 2000, SCIENCE, V287, P1471, DOI 10.1126/science.287.5457.1471 Morales AM, 1998, SCIENCE, V279, P208, DOI 10.1126/science.279.5348.208 KRTI J, 1998, PHYS REV B, V58, P8869 Hong S, 1997, PHYS REV B, V55, P9975, DOI 10.1103/PhysRevB.55.9975 GONZE X, 1992, PHYS REV LETT, V68, P3603, DOI 10.1103/PhysRevLett.68.3603 GIANNOZZI P, 1991, PHYS REV B, V43, P7231, DOI 10.1103/PhysRevB.43.7231 TROULLIER N, 1991, PHYS REV B, V43, P1993, DOI 10.1103/PhysRevB.43.1993 BARONI S, 1987, PHYS REV LETT, V58, P1861, DOI 10.1103/PhysRevLett.58.1861 BARONI S, 1986, PHYS REV B, V33, P5969, DOI 10.1103/PhysRevB.33.5969 BRUESCH P, 1986, PHONONS THEORY EXPT, V2 CARDONA M, 1982, LIGHT SCATTERING SOL, V2 RICHTER H, 1981, SOLID STATE COMMUN, V39, P625, DOI 10.1016/0038-1098(81)90337-9 COHEN ML, 1975, PHYS REV B, V12, P5575, DOI 10.1103/PhysRevB.12.5575Yang, Li Chou, M. Y.U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DEFG02-97ER45632]This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DEFG02-97ER45632. Computational resources are provided by the National Energy Research Scientific Computing Center (NERSC).AMER CHEMICAL SOCWASHINGTON

Abstract:

n/a

Notes:

ISI Document Delivery No.: 791CNTimes Cited: 0Cited Reference Count: 1Cited References: Lee CM, 2010, APPL PHYS LETT, V96Lee, C. M. Lee, Richard C. H. Ruan, W. Y. Chou, M. Y.AMER INST PHYSICSMELVILLE

Abstract:

It has been demonstrated that replacing Li(2)NH with the mixed imide Li(2)Mg(NH)(2) improves the reaction conditions for the hydrogen-storage system Li(2)NH + H(2) <-> LiNH(2) + LiH, at the expense of reducing the gravitational hydrogen capacity from 6.5% to 5.6%. In this article, we report from first-principles calculations a possible mixed imide Li(6)Mg(NH)(4) that has less Mg concentration and higher gravimetric capacity for hydrogen storage than Li(2)Mg(NH)(2). We find that Li(6)Mg(NH)(4) is thermodynamically more stable than the phase-separated mixture of Li(2)Mg(NH)(2) and Li(2)NH over a large temperature range. The reaction LiH + 1/4Mg(NH(2))(2) + 1/2LiNH(2) <-> 1/4Li(6)Mg(NH)(4) + H(2) can be completed via two steps and releases 6.0 wt % hydrogen in total, at a temperature about 40 degrees C lower than that for the cycling between LiNH(2) and Li(2)NH.

Notes:

ISI Document Delivery No.: 713LLTimes Cited: 0Cited Reference Count: 20Cited References: Mueller T, 2010, PHYS REV B, V82, DOI 10.1103/PhysRevB.82.174307 Michel KJ, 2009, J PHYS CHEM C, V113, P14551 Ma Z, 2008, J APPL PHYS, V104, DOI 10.1063/1.3003067 Rijssenbeek J, 2008, J ALLOY COMPD, V454, P233, DOI 10.1016/j.jallcom.2006.12.008 Akbarzadeh AR, 2007, ADV MATER, V19, P3233 Wang Y, 2007, PHYS REV B, V76 Yang J, 2007, J ALLOY COMPD, V430, P334, DOI 10.1016/j.jallcom.2006.05.039 Mueller T, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.134104 Balogh MP, 2006, J ALLOY COMPD, V420, P326, DOI 10.1016/j.jallcom.2005.11.018 Luo WF, 2006, J ALLOY COMPD, V407, P274, DOI 10.1016/j.jallcom.2005.06.046 Herbst JF, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.125120 Kojima Y, 2005, J ALLOY COMPD, V395, P236, DOI 10.1016/j.jallcom.2004.10.063 Leng HY, 2004, J PHYS CHEM B, V108, P8763, DOI 10.1021/jp048002j Ichikawa T, 2004, J PHYS CHEM B, V108, P7887, DOI 10.1021/jp049968y Hu YH, 2003, J PHYS CHEM A, V107, P9737, DOI 10.1021/jp036257b Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 PERDEW JP, 1992, PHYS REV B, V46, P6671, DOI 10.1103/PhysRevB.46.6671 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 MICELI G, ARXIV10091488Zhang, Feng Wang, Yan Chou, M. Y.US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DE-FG02-05ER46229]; Office of Science of the US Department of Energy[DE-AC02-05CH11231]This work is supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award DE-FG02-05ER46229. This research uses resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

A twisted graphene bilayer consists of two graphene monolayers rotated by an angle. with respect to each other. Theory predicts that charge-neutral twisted graphene bilayers display a drastic reduction of their Fermi velocity v(F) for 0 less than or similar to 0 less than or similar to 20 degrees and 40 less than or similar to 0 less than or similar to 60 degrees. In this paper we present evidence for an additional anisotropic reduction of v(F) in the presence of external electrostatic fields. We also discuss in quantitative detail velocity renormalization for other relevant bands in the vicinity of the K point. Except for a rigid energy shift, electrostatic fields and doping by metal atoms give rise to similar renormalization of the band structure of twisted graphene bilayers.

Notes:

ISI Document Delivery No.: 803BPTimes Cited: 0Cited Reference Count: 47Cited References: Hicks J, 2011, PHYS REV B, V83 Luican A, 2011, PHYS REV LETT, V106 Morell ES, 2010, PHYS REV B, V82 Profumo REV, 2010, PHYS REV B, V82 Kasry A, 2010, ACS NANO, V4, P3839 Bistritzer R, 2010, PHYS REV B, V81 Coletti C, 2010, PHYS REV B, V81 Shi YM, 2010, ACS NANO, V4, P2689 Mele EJ, 2010, PHYS REV B, V81 Shallcross S, 2010, PHYS REV B, V81 Sun D, 2010, PHYS REV LETT, V104 de Laissardiere GT, 2010, NANO LETT, V10, P804 Tzalenchuk A, 2010, NAT NANOTECHNOL, V5, P186 Lin YM, 2010, SCIENCE, V327, P662, DOI 10.1126/science.1184289 Li XS, 2009, NANO LETT, V9, P4359 Sprinkle M, 2009, PHYS REV LETT, V103 Moon JS, 2009, IEEE ELECTR DEVICE L, V30, P650, DOI 10.1109/LED.2009.2020699 Poncharal P, 2009, PHYS REV B, V79 Miller DL, 2009, SCIENCE, V324, P924 Kim KS, 2009, NATURE, V457, P706 Castro Neto AH, 2009, REV MOD PHYS, V81, P109 Reina A, 2009, NANO LETT, V9, P30, DOI 10.1021/nl801827v Shallcross S, 2008, J PHYS-CONDENS MAT, V20, DOI 10.1088/0953-8984/20/45/454224 Poncharal P, 2008, PHYS REV B, V78, DOI 10.1103/PhysRevB.78.113407 Zhou SY, 2008, PHYS REV LETT, V101 Hass J, 2008, J PHYS-CONDENS MAT, V20, DOI 10.1088/0953-8984/20/32/323202 Kedzierski J, 2008, IEEE T ELECTRON DEV, V55, P2078, DOI 10.1109/TED.2008.926593 Shallcross S, 2008, PHYS REV LETT, V101 Ni ZH, 2008, PHYS REV B, V77, DOI 10.1103/PhysRevB.77.235403 Chen JH, 2008, NAT PHYS, V4, P377, DOI 10.1038/nphys935 Sutter PW, 2008, NAT MATER, V7, P406, DOI 10.1038/nmat2166 Hass J, 2008, PHYS REV LETT, V100 Artacho E, 2008, J PHYS-CONDENS MAT, V20, DOI 10.1088/0953-8984/20/6/064208 Oostinga JB, 2008, NAT MATER, V7, P151, DOI 10.1038/nmat2082 dos Santos JMBL, 2007, PHYS REV LETT, V99 Latil S, 2007, PHYS REV B, V76 de Heer WA, 2007, SOLID STATE COMMUN, V143, P92, DOI 10.1016/j.ssc.2007.04.023 McCann E, 2007, SOLID STATE COMMUN, V143, P110, DOI 10.1016/j.ssc.2007.03.054 Bostwick A, 2007, NAT PHYS, V3, P36, DOI 10.1038/nphys477 Ohta T, 2006, SCIENCE, V313, P951, DOI 10.1126/science.1130681 Soler JM, 2002, J PHYS-CONDENS MAT, V14, P2745, DOI 10.1088/0953-8984/14/11/302 Junquera J, 2001, PHYS REV B, V64, DOI 10.1103/PhysRevB.64.235111 TROULLIER N, 1991, PHYS REV B, V43, P1993, DOI 10.1103/PhysRevB.43.1993 PERDEW JP, 1981, PHYS REV B, V23, P5048, DOI 10.1103/PhysRevB.23.5048 CEPERLEY DM, 1980, PHYS REV LETT, V45, P566, DOI 10.1103/PhysRevLett.45.566 WALLACE PR, 1947, PHYS REV, V71, P622, DOI 10.1103/PhysRev.71.622 BISTRITZER R, PNAS EARLY EDITIONXian, Lede Barraza-Lopez, Salvador Chou, M. Y.National Science Foundation[DMR-08-20382]; US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DEFG02-97ER45632]; Office of Science of the US Department of Energy[DE-AC02-05CH11231]; National Science Foundation TeraGrid[TG-PHY090002]We are grateful to Edward Conrad and Markus E. Kindermann for insightful discussions. We acknowledge the support by the Georgia Tech Materials Research Science and Engineering Center (MRSEC) funded by the National Science Foundation under Grant No. DMR-08-20382 and by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DEFG02-97ER45632. This research used computational resources at the National Energy Research Scientific Computing Center supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231, and the National Science Foundation TeraGrid (TG-PHY090002).AMER PHYSICAL SOCCOLLEGE PK

Abstract:

It has been suggested that the diffusion of AlH(3) vacancies plays an essential role in the decomposition of NaAlH(4), a prototypical material for hydrogen storage. We find from first-principles calculations that the AlH(3) vacancy induces several isolated vibrational modes that are highly localized in the vacancy region with frequencies within the phonon gaps of pure NaAlH(4) in both the a and g phases. Thus, the proposed existence of AlH(3) vacancies in the dehydrogenation reaction of NaAlH(4) can be possibly confirmed with the experimental detection of these unique vibrational modes associated with the AlH(3) vacancy.

Notes:

ISI Document Delivery No.: 802NDTimes Cited: 1Cited Reference Count: 22Cited References: Ivancic TM, 2010, J PHYS CHEM LETT, V1, P2412 Sakaki K, 2010, J PHYS CHEM C, V114, P6869 Wood BC, 2010, PHYS REV LETT, V104 Wilson-Short GB, 2009, PHYS REV B, V80 Giannozzi P, 2009, J PHYS-CONDENS MAT, V21 Gunaydin H, 2008, P NATL ACAD SCI USA, V105, P3673, DOI 10.1073/pnas.0709224105 Kadono R, 2008, PHYS REV LETT, V100 JENSEN C, 2008, ALANATES HYDROGEN ST, P381 Peles A, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.214101 Yukawa H, 2007, J ALLOY COMPD, V446, P242, DOI 10.1016/j.jallcom.2007.02.071 Peles A, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.184302 Lovvik OM, 2006, APPL PHYS LETT, V88 Lovvik OM, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.054103 Palumbo O, 2005, J PHYS CHEM B, V109, P1168, DOI 10.1021/jp0460893 Ke XZ, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.024117 Majzoub EH, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.024118 Bogdanovic B, 2000, J ALLOY COMPD, V302, P36, DOI 10.1016/S0925-8388(99)00663-5 Bogdanovic B, 1997, J ALLOY COMPD, V253, P1, DOI 10.1016/S0925-8388(96)03049-6 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 PERDEW JP, 1992, PHYS REV B, V46, P6671, DOI 10.1103/PhysRevB.46.6671 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892Zhang, Feng Wang, Yan Chou, M. Y.U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DE-FG02-05ER46229]; Office of Science of the U.S. Department of Energy[DE-AC02-05CH11231]This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-05ER46229. This research uses resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy Under Contract No. DE-AC02-05CH11231.ROYAL SOC

2010

Abstract:

In this paper, we study the low-lying energy spectra of a two-dimensional (2D) graphene-based magnetic dot in a perpendicular and radially inhomogeneous magnetic field with the use of the massless Dirac-Weyl equation. Numerical calculations are performed using 2D harmonic basis states for direct diagonalization. Effects of both the dot size and the magnetic field on the low-lying energy spectra are discussed.

Notes:

ISI Document Delivery No.: 645AATimes Cited: 0Cited Reference Count: 22Cited References: Nasir R, 2010, J PHYS-CONDENS MAT, V22 Pereira JM, 2009, PHYS REV B, V79 Masir MR, 2009, PHYS REV B, V79 Recher P, 2009, PHYS REV B, V79 Schnez S, 2009, APPL PHYS LETT, V94 Castro Neto AH, 2009, REV MOD PHYS, V81, P109 Schnez S, 2008, PHYS REV B, V78, DOI 10.1103/PhysRevB.78.195427 Beenakker CWJ, 2008, REV MOD PHYS, V80, P1337, DOI 10.1103/RevModPhys.80.1337 Ponomarenko LA, 2008, SCIENCE, V320, P356, DOI 10.1126/science.1154663 De Martino A, 2007, SOLID STATE COMMUN, V144, P547, DOI 10.1016/j.ssc.2007.03.062 Chen HY, 2007, PHYS REV LETT, V98 Novoselov KS, 2007, SCIENCE, V315, P1379, DOI 10.1126/science.1137201 De Martino A, 2007, PHYS REV LETT, V98 Gunlycke D, 2007, PHYS REV B, V75 Katsnelson MI, 2006, NAT PHYS, V2, P620, DOI 10.1038/nphys384 Novoselov KS, 2005, NATURE, V438, P197, DOI 10.1038/nature04233 Zhang YB, 2005, NATURE, V438, P201, DOI 10.1038/nature04235 Berger C, 2004, J PHYS CHEM B, V108, P19912, DOI 10.1021/jp040650f Novoselov KS, 2004, SCIENCE, V306, P666, DOI 10.1126/science.1102896 DIVINCENZO DP, 1984, PHYS REV B, V29, P1685, DOI 10.1103/PhysRevB.29.1685 SEMENOFF GW, 1984, PHYS REV LETT, V53, P2449, DOI 10.1103/PhysRevLett.53.2449 Klein O, 1929, Z PHYS, V53, P157, DOI 10.1007/BF01339716Lee, C. M. Lee, Richard C. H. Ruan, W. Y. Chou, M. Y.US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DE-FG02-97ER45632]WYR and MYC acknowledge support by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-FG02-97ER45632.IOP PUBLISHING LTDBRISTOL

Abstract:

We presented a detailed study of the oxidation functional groups (epoxide and hydroxyl) on graphene based on density-functional calculations. Effects of single functional groups and their various combinations on the electronic and structural properties are investigated. It is found that single functional groups can induce interesting electronic bound states in graphene. Detailed energetics analysis shows that epoxy and hydroxyl groups tend to aggregate on the graphene plane. Investigations of possible ordered structures with different compositions of epoxy and hydroxyl groups show that the hydroxyl groups could form chainlike structures stabilized by the hydrogen bonding between these groups, in close proximity of the epoxy groups. Our calculations indicate that the energy gap of graphene oxide can be tuned in a large range of 0-4.0 eV, suggesting that functionalization of graphene by oxidation will significantly alter the electronic properties of graphene.

Notes:

ISI Document Delivery No.: 645SMTimes Cited: 5Cited Reference Count: 50Cited References: Xiang HJ, 2010, PHYS REV B, V82 Xu ZP, 2010, NANOTECHNOLOGY, V21 Eda G, 2009, J PHYS CHEM C, V113, P15768 Yan JA, 2009, PHYS REV LETT, V103 Li ZY, 2009, J AM CHEM SOC, V131, P6320 Guisinger NP, 2009, NANO LETT, V9, P1462 Luo ZT, 2009, APPL PHYS LETT, V94 Lahaye RJWE, 2009, PHYS REV B, V79 Mkhoyan KA, 2009, NANO LETT, V9, P1058 Elias DC, 2009, SCIENCE, V323, P610 Luo ZT, 2009, J AM CHEM SOC, V131, P898 Jung I, 2008, NANO LETT, V8, P4283, DOI 10.1021/nl8019938 Cai WW, 2008, SCIENCE, V321, P1815, DOI 10.1126/science.1162369 Boukhvalov DW, 2008, J AM CHEM SOC, V130, P10697, DOI 10.1021/ja8021686 Wu XS, 2008, PHYS REV LETT, V101 Eda G, 2008, NAT NANOTECHNOL, V3, P270, DOI 10.1038/nnano.2008.83 Pandey D, 2008, SURF SCI, V602, P1607, DOI 10.1016/j.susc.2008.02.025 Li D, 2008, NAT NANOTECHNOL, V3, P101, DOI 10.1038/nnano.2007.451 Boukhvalov DW, 2008, PHYS REV B, V77 Kudin KN, 2008, NANO LETT, V8, P36, DOI 10.1021/nl071822y Paci JT, 2007, J PHYS CHEM C, V111, P18099, DOI 10.1021/jp075799g Gilje S, 2007, NANO LETT, V7, P3394, DOI 10.1021/nl0717715 Gomez-Navarro C, 2007, NANO LETT, V7, P3499, DOI 10.1021/nl072090c Dikin DA, 2007, NATURE, V448, P457, DOI 10.1038/nature06016 Rutter GM, 2007, SCIENCE, V317, P219, DOI 10.1126/science.1142882 Stankovich S, 2007, CARBON, V45, P1558, DOI 10.1016/j.carbon.2007.02.034 Sofo JO, 2007, PHYS REV B, V75, DOI 10.1103/PhysRevB.75.153401 Wehling TO, 2007, PHYS REV B, V75, DOI 10.1103/PhysRevB.75.125425 Buchsteiner A, 2006, J PHYS CHEM B, V110, P22328, DOI 10.1021/jp0641132 Li JL, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.176101 Schniepp HC, 2006, J PHYS CHEM B, V110, P8535, DOI 10.1021/jp060936f Ruffieux P, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.153403 Baroni S, 2001, REV MOD PHYS, V73, P515, DOI 10.1103/RevModPhys.73.515 Kelly KF, 2000, P NATL ACAD SCI USA, V97, P10318, DOI 10.1073/pnas.190325397 Ruffieux P, 2000, PHYS REV LETT, V84, P4910, DOI 10.1103/PhysRevLett.84.4910 Bengtsson L, 1999, PHYS REV B, V59, P12301, DOI 10.1103/PhysRevB.59.12301 Lerf A, 1998, J PHYS CHEM B, V102, P4477, DOI 10.1021/jp9731821 He HY, 1998, CHEM PHYS LETT, V287, P53, DOI 10.1016/S0009-2614(98)00144-4 NAKAJIMA T, 1994, CARBON, V32, P469, DOI 10.1016/0008-6223(94)90168-6 KRESSE G, 1993, PHYS REV B, V47, P558, DOI 10.1103/PhysRevB.47.558 MERMOUX M, 1991, CARBON, V29, P469, DOI 10.1016/0008-6223(91)90216-6 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 CAREY FA, 1990, ADV ORGANIC CHEM MIZES HA, 1989, SCIENCE, V244, P559, DOI 10.1126/science.244.4904.559 NAKAJIMA T, 1988, CARBON, V26, P357, DOI 10.1016/0008-6223(88)90227-8 MONKHORST HJ, 1976, PHYS REV B, V13, P5188, DOI 10.1103/PhysRevB.13.5188 CLAUSS A, 1957, Z ANORG ALLG CHEM, V291, P205, DOI 10.1002/zaac.19572910502 RUESS G, 1945, KOLLOID Z Z POLYM, V110, P17 ECHTERMEYER TJ, ARXIV07122026 TRAMBLY G, COMMUNICATIONYan, Jia-An Chou, M. Y.Department of Energy[DE-FG02-97ER45632]; National Science Foundation[DMR-08-20382]; Office of Science of the U.S. Department of Energy[DE-AC02-05CH11231]We thank P.N. First and W.Y. Ruan for discussions and S. Barraza-Lopez for the assistance with some plots. This work is supported by the Department of Energy (Grant No. DE-FG02-97ER45632). We acknowledge interaction with the Georgia Tech MRSEC funded by National Science Foundation (Grant No. DMR-08-20382). This research used computational resources at the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and the National Science Foundation TeraGrid resources provided by the Texas Advanced Computing Center (TACC).AMER PHYSICAL SOCCOLLEGE PK

Abstract:

Lithium imide (Li2NH) has been considered as a promising medium for hydrogen storage with the following reaction: LiNH(2)+LiH <-> Li(2)NH+H(2). All possible phases involved in the reaction need to be fully characterized in order to understand the right pathway connecting the two end compounds LiNH(2) and Li(2)NH and to further improve its reaction condition to meet the requirements of practical applications. We study from first-principles calculations the possible intermediate compounds Li(2-x)NH(1+x) between Li(2)NH and LiNH(2). Based on the energetics results, possible intermediate phases are identified for 0

Notes:

ISI Document Delivery No.: 652KETimes Cited: 1Cited Reference Count: 23Cited References: Crivello JC, 2010, PHYS REV B, V81 Rijssenbeek J, 2008, J ALLOY COMPD, V454, P233, DOI 10.1016/j.jallcom.2006.12.008 Shaw LL, 2008, J POWER SOURCES, V177, P500, DOI 10.1016/j.jpowsour.2007.11.029 HECTOR LG, 2008, J PHYS CONDENS MATT, V20, DOI 10.1088/0953-8984/20/6/064229 Wang Y, 2007, PHYS REV B, V76 David WIF, 2007, J AM CHEM SOC, V129, P1594, DOI 10.1021/ja066016s Mueller T, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.134104 Balogh MP, 2006, J ALLOY COMPD, V420, P326, DOI 10.1016/j.jallcom.2005.11.018 Magyari-Kope B, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.220101 Luo WF, 2006, J ALLOY COMPD, V407, P274, DOI 10.1016/j.jallcom.2005.06.046 Zhang CJ, 2005, J PHYS CHEM B, V109, P22089, DOI 10.1021/jp054961h Herbst JF, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.125120 Noritake T, 2005, J ALLOY COMPD, V393, P264, DOI 10.1016/j.jallcom.2004.09.063 Ohoyama K, 2005, J PHYS SOC JPN, V74, P483, DOI 10.1143/JPSJ.74.483 Leng HY, 2004, J PHYS CHEM B, V108, P8763, DOI 10.1021/jp048002j Ichikawa T, 2004, J PHYS CHEM B, V108, P7887, DOI 10.1021/jp049968y Chen P, 2003, J PHYS CHEM B, V107, P10967, DOI 10.1021/jp034149j Chen P, 2002, NATURE, V420, P302, DOI 10.1038/nature01210 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 PERDEW JP, 1992, PHYS REV B, V46, P6671, DOI 10.1103/PhysRevB.46.6671 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 MONKHORST HJ, 1976, PHYS REV B, V13, P5188, DOI 10.1103/PhysRevB.13.5188Zhang, Feng Wang, Yan Chou, M. Y.U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering[DE-FG02-05ER46229]; Office of Science of the U.S. Department of Energy[DE-AC02-05CH11231]This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-FG02-05ER46229. This research uses resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

Both the size and the magnetic-field dependences of low-lying spectra of two-dimensional (2D) graphene based magnetic dot and ring in perpendicular inhomogeneous magnetic fields, where the magnetic field is zero inside the dot and ring, and constant elsewhere, are studied by the massless Dirac-Weyl equation. Numerical results obtained from direct diagonalization with 2D harmonic basis show that, under nonuniform magnetic fields, the higher Landau levels (N >= 1) for such massless Dirac electron interacting system in general become nondegenerate and split into discrete angular momentum states with level crossings with the lowest one (N=0) being an exception. (C) 2010 American Institute of Physics. [doi:10.1063/1.3435478]

Notes:

ISI Document Delivery No.: 603BPTimes Cited: 3Cited Reference Count: 14Cited References: Castro Neto AH, 2009, REV MOD PHYS, V81, P109 Beenakker CWJ, 2008, REV MOD PHYS, V80, P1337, DOI 10.1103/RevModPhys.80.1337 De Martino A, 2007, SOLID STATE COMMUN, V144, P547, DOI 10.1016/j.ssc.2007.03.062 Chen HY, 2007, PHYS REV LETT, V98 Novoselov KS, 2007, SCIENCE, V315, P1379, DOI 10.1126/science.1137201 De Martino A, 2007, PHYS REV LETT, V98 Gunlycke D, 2007, PHYS REV B, V75 Katsnelson MI, 2006, NAT PHYS, V2, P620, DOI 10.1038/nphys384 Novoselov KS, 2005, NATURE, V438, P197, DOI 10.1038/nature04233 Zhang YB, 2005, NATURE, V438, P201, DOI 10.1038/nature04235 Novoselov KS, 2004, SCIENCE, V306, P666, DOI 10.1126/science.1102896 DIVINCENZO DP, 1984, PHYS REV B, V29, P1685, DOI 10.1103/PhysRevB.29.1685 SEMENOFF GW, 1984, PHYS REV LETT, V53, P2449, DOI 10.1103/PhysRevLett.53.2449 Klein O, 1929, Z PHYS, V53, P157, DOI 10.1007/BF01339716Lee, C. M. Lee, Richard C. H. Ruan, W. Y. Chou, M. Y.Department of Energy[DE-FG02-97ER45632]; National Science Foundation[DMR-02-05328]This work is supported by the Department of Energy under Grant No. DE-FG02-97ER45632 and by the National Science Foundation under Grant No. DMR-02-05328.AMER INST PHYSICSMELVILLE

Abstract:

In this paper, we present the direct observation of quantum size effects (QSE) on the work function in ultrathin Pb films. By using scanning tunneling microscopy and spectroscopy, we show that the very existence of quantum well states (QWS) in these ultrathin films profoundly affects the measured tunneling decay constant kappa, resulting in a very rich phenomenon of "quantum oscillations" in kappa as a function of thickness, L, and bias voltage, V(s). More specifically, we find that the phase of the quantum oscillations in kappa vs. L depends sensitively upon the bias voltage, which often results in a total phase reversal at different biases. On the other hand, at very low sample bias (vertical bar V(s)vertical bar < 0.03 V) the measurement of kappa vs. L accurately reflects the quantum size effect on the work function. In particular, the minima in the quantum oscillations of kappa vs. L occur at the locations where QWS cross the Fermi energy, thus directly unraveling the QSE on the work function in ultrathin films, which was predicted more than three decades ago. This further clarifies several contradictions regarding the relationship between the QWS locations and the work function.

Notes:

ISI Document Delivery No.: 628TJTimes Cited: 4Cited Reference Count: 21Cited References: Miller T, 2009, PHYS REV LETT, V102 Qin SY, 2009, SCIENCE, V324, P1314 Liu X, 2008, APPL PHYS LETT, V93 Ozer MM, 2007, SCIENCE, V316, P1594, DOI 10.1126/science.1142159 Ma XC, 2007, P NATL ACAD SCI USA, V104, P9204, DOI 10.1073/pnas.0611024104 Qi Y, 2007, APPL PHYS LETT, V90 Ozer MM, 2006, NAT PHYS, V2, P173, DOI 10.1038/nphys244 Eom D, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.027005 JIA Y, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.035433 Czoschke P, 2004, PHYS REV LETT, V93, DOI 10.1103/PhysRevLett.93.036103 Paggel JJ, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.233403 Wei CM, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.233408 CHANG SH, 2002, PHYS REV B, V66 HUPALO M, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.161410 Su WB, 2001, PHYS REV LETT, V86, P5116, DOI 10.1103/PhysRevLett.86.5116 Luh DA, 2001, SCIENCE, V292, P1131, DOI 10.1126/science.292.5519.1131 Yeh V, 2000, PHYS REV LETT, V85, P5158, DOI 10.1103/PhysRevLett.85.5158 Zhang ZY, 1998, PHYS REV LETT, V80, P5381, DOI 10.1103/PhysRevLett.80.5381 Smith AR, 1996, SCIENCE, V273, P226, DOI 10.1126/science.273.5272.226 STROSCIO JA, 1986, PHYS REV LETT, V57, P2579, DOI 10.1103/PhysRevLett.57.2579 SCHULTE FK, 1976, SURF SCI, V55, P427, DOI 10.1016/0039-6028(76)90250-8Kim, Jungdae Qin, Shengyong Yao, Wang Niu, Qian Chou, M. Y. Shih, Chih-KangNSF[DMR-0906025, CMMI-0928664]; Welch Foundation[F-1672]; Texas Advanced Research Program[003658-0037-2007]; DOE[DE-FG02-97ER45632]This work was supported by NSF Grant DMR-0906025, CMMI-0928664, Welch Foundation F-1672, and Texas Advanced Research Program 003658-0037-2007. M.-Y.C. acknowledges support by DOE Grant DE-FG02-97ER45632.NATL ACAD SCIENCESWASHINGTON

Abstract:

We report on a first-principles study of the conductance through graphene suspended between Al contacts as a function of junction length, width, and orientation. The charge transfer at the leads and into the freestanding section gives rise to an electron-hole asymmetry in the conductance and in sufficiently long junctions induces two conductance minima at the energies of the Dirac points for suspended and clamped regions, respectively. We obtain the potential profile along a junction caused by doping and provide parameters for effective model calculations of the junction conductance with weakly interacting metallic leads.

Notes:

ISI Document Delivery No.: 557JDTimes Cited: 23Cited Reference Count: 33Cited References: Blake P, 2009, SOLID STATE COMMUN, V149, P1068 Geim AK, 2009, SCIENCE, V324, P1530 Farmer DB, 2009, APPL PHYS LETT, V94 Khomyakov PA, 2009, PHYS REV B, V79 Ran QS, 2009, APPL PHYS LETT, V94 Golizadeh-Mojarad R, 2009, PHYS REV B, V79 Castro Neto AH, 2009, REV MOD PHYS, V81, P109 Farmer DB, 2009, NANO LETT, V9, P388 Huard B, 2008, PHYS REV B, V78, DOI 10.1103/PhysRevB.78.121402 Lee EJH, 2008, NAT NANOTECHNOL, V3, P486, DOI 10.1038/nnano.2008.172 Giovannetti G, 2008, PHYS REV LETT, V101 Danneau R, 2008, PHYS REV LETT, V100 Nemec N, 2008, PHYS REV B, V77, DOI 10.1103/PhysRevB.77.125420 Martin J, 2008, NAT PHYS, V4, P144, DOI 10.1038/nphys781 WANG X, 2008, PHYS REV LETT, V100, DOI 10.1103/PhysRevLett.100.206803 Ozyilmaz B, 2007, PHYS REV LETT, V99 Avouris P, 2007, NAT NANOTECHNOL, V2, P605, DOI 10.1038/nnano.2007.300 Blanter YM, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.155433 Robinson JP, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.115430 Williams JR, 2007, SCIENCE, V317, P638, DOI 10.1126/science.1144657 Huard B, 2007, PHYS REV LETT, V98 Han MY, 2007, PHYS REV LETT, V98 Heersche HB, 2007, NATURE, V446, P56, DOI 10.1038/nature05555 Tworzydlo J, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.246802 Berger C, 2006, SCIENCE, V312, P1191, DOI 10.1126/science.1125925 Rocha AR, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.085414 Rocha AR, 2005, NAT MATER, V4, P335, DOI 10.1038/nmat1349 Berger C, 2004, J PHYS CHEM B, V108, P19912, DOI 10.1021/jp040650f Novoselov KS, 2004, SCIENCE, V306, P666, DOI 10.1126/science.1102896 Soler JM, 2002, J PHYS-CONDENS MAT, V14, P2745, DOI 10.1088/0953-8984/14/11/302 Junquera J, 2001, PHYS REV B, V64, DOI 10.1103/PhysRevB.64.235111 TROULLIER N, 1993, PHYS REV B, V43, P1991 PERDEW JP, 1981, PHYS REV B, V23, P5048, DOI 10.1103/PhysRevB.23.5048Barraza-Lopez, Salvador Vanevic, Mihajlo Kindermann, Markus Chou, M. Y.Department of Energy[DE-FG02-97ER45632]; National Science Foundation[DMR-02-05328]; NCSA[TG-PHY090002]; NERSCWe thank L. Xian, K. Park, and E. Yepez for helpful discussions. This work is supported by the Department of Energy (Grant No. DE-FG02-97ER45632). We acknowledge interaction with the Georgia Tech MRSEC funded by the National Science Foundation (Grant No. DMR-02-05328) and computer support from Teragrid at NCSA (TG-PHY090002, Cobalt supercomputer) and NERSC.AMER PHYSICAL SOCCOLLEGE PK

2009

Abstract:

We present a first-principles study of the electron-phonon (e-ph) interactions and their contributions to the linewidths for the optical-phonon modes at Gamma and K in one-layer to three-layer graphene. It is found that, due to the interlayer coupling and the stacking geometry, the high-frequency optical-phonon modes in few-layer graphene couple with different valence and conduction bands, giving rise to different e-ph interaction strengths for these modes. Some of the multilayer optical modes derived from the Gamma-E(2g) mode of monolayer graphene exhibit slightly higher frequencies and much reduced linewidths. In addition, the linewidths of K-A(1)(') related modes in multilayers depend on the stacking pattern and decrease with increasing layer numbers.

Notes:

ISI Document Delivery No.: 427GXTimes Cited: 9Cited Reference Count: 37Cited References: Park CH, 2008, NANO LETT, V8, P4229, DOI 10.1021/nl801884n Gonzalez J, 2008, PHYS REV LETT, V101 Hwang EH, 2008, PHYS REV LETT, V101 Yan J, 2008, PHYS REV LETT, V101 Zhou SY, 2008, PHYS REV LETT, V101 Tse WK, 2008, PHYS REV LETT, V101 Hwang EH, 2008, PHYS REV B, V77 Yan JA, 2008, PHYS REV B, V77, DOI 10.1103/PhysRevB.77.125401 Calandra M, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.205411 Bonini N, 2007, PHYS REV LETT, V99 Park CH, 2007, PHYS REV LETT, V99 Bostwick A, 2007, SOLID STATE COMMUN, V143, P63, DOI 10.1016/j.ssc.2007.04.034 Ferrari AC, 2007, SOLID STATE COMMUN, V143, P47, DOI 10.1016/j.ssc.2007.03.052 Ohta T, 2007, PHYS REV LETT, V98 Yan J, 2007, PHYS REV LETT, V98 Akhmerov AR, 2007, PHYS REV LETT, V98 Rycerz A, 2007, NAT PHYS, V3, P172, DOI 10.1038/nphys547 Giustino F, 2007, PHYS REV LETT, V98 Ohta T, 2006, SCIENCE, V313, P951, DOI 10.1126/science.1130681 Latil S, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.036803 Lazzeri M, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.155426 Lazzeri M, 2005, PHYS REV LETT, V95, DOI 10.1103/PhysRevLett.95.236802 Kampfrath T, 2005, PHYS REV LETT, V95, DOI 10.1103/PhysRevLett.95.187403 Zhang YB, 2005, APPL PHYS LETT, V86, DOI 10.1063/1.1862334 Berger C, 2004, J PHYS CHEM B, V108, P19912, DOI 10.1021/jp040650f Piscanec S, 2004, PHYS REV LETT, V93, DOI 10.1103/PhysRevLett.93.185503 Novoselov KS, 2004, SCIENCE, V306, P666, DOI 10.1126/science.1102896 Mahan GD, 2003, PHYS REV B, V68, DOI 10.1103/PhysRevB.68.125409 Baroni S, 2001, REV MOD PHYS, V73, P515, DOI 10.1103/RevModPhys.73.515 Woods LM, 2000, PHYS REV B, V61, P10651, DOI 10.1103/PhysRevB.61.10651 Yao Z, 2000, PHYS REV LETT, V84, P2941, DOI 10.1103/PhysRevLett.84.2941 TROULLIER N, 1991, PHYS REV B, V43, P1993, DOI 10.1103/PhysRevB.43.1993 MENENDEZ J, 1984, PHYS REV B, V29, P2051, DOI 10.1103/PhysRevB.29.2051 GRIMVALL G, 1981, ELECT PHONON INTERAC NEMANICH RJ, 1977, SOLID STATE COMMUN, V23, P117, DOI 10.1016/0038-1098(77)90663-9 ALLEN PB, 1974, PHYS REV B, V9, P4733, DOI 10.1103/PhysRevB.9.4733 ALLEN PB, 1972, PHYS REV B, V6, P2577, DOI 10.1103/PhysRevB.6.2577Yan, Jia-An Ruan, W. Y. Chou, M. Y.Department of Energy[DEFG02-97ER45632]; National Science Foundation[DMR-08-20382]; National Energy Research Scientific Computing Center (NERSC); U. S. Department of Energy[DE-AC03-76SF00098]; National Science Foundation Teragrid resourcesWe acknowledge helpful discussions with M. Wierzbowska and S. Piscanec. J. A. Y thanks F. Giustino and C.- H. Park for critical reading of the manuscript. This work is supported by the Department of Energy (Grant No. DEFG02-97ER45632) and by the National Science Foundation (Grant No. DMR-08-20382). The computation used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the U. S. Department of Energy (Grant No. DE-AC03-76SF00098), and the National Science Foundation Teragrid resources.AMER PHYSICAL SOCCOLLEGE PK 

Abstract:

We present a first-principles investigation to study the possible alloy phases of sodium and lithium alanates. Structural and energetics properties of alloy systems Na(1-x)Li(x)AlH(4) and Na(3(1-x))Li(3x)AlH(6) are studied via phase interpolation. Alloy system Na(1-x)Li(x)AlH(4) is found to have a small mixing energy (<5 kj/mol). The equilibrium structure undergoes a transition from a tetragonal structure to a monoclinic structure between x = 0.25 and 0.5. Within each structure the cell volume decreases with increasing x, which can be explained by Li having a smaller ion size than Na. Alloy system Na(3(1-x))Li(3x)AlH(6) is also studied, and one intermediate composition Na(2)LiAlH(6) is found to be stable in agreement with experimental findings. (C) 2009 Elsevier B.V. All rights reserved.

Notes:

ISI Document Delivery No.: 458XRTimes Cited: 1Cited Reference Count: 23Cited References: Graetz J, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.184115 Brinks HW, 2005, J ALLOY COMPD, V392, P27, DOI 10.1016/j.jallcom.2004.09.006 Fossdal A, 2005, J ALLOY COMPD, V387, P47, DOI 10.1016/j.jallcom.2004.06.050 Peles A, 2004, PHYS REV B, V70, DOI 10.1103/PhysRevB.70.165105 Lovvik OM, 2004, EUROPHYS LETT, V67, P607, DOI 10.1209/epl/i2004-10105-x de Dompablo MEAY, 2004, J ALLOY COMPD, V364, P6 Vajeeston P, 2003, PHYS REV B, V68, DOI 10.1103/PhysRevB.68.212101 Hauback BC, 2003, J ALLOY COMPD, V358, P142, DOI 10.1016/S0925-8388(03)00136-1 Brinks HW, 2003, J ALLOY COMPD, V354, P143, DOI 10.1016/S0925-8388(02)01348-8 ZUTTEL A, 2003, MATER TODAY, V6, P24, DOI 10.1016/S1369-7021(03)00922-2 Hauback BC, 2002, J ALLOY COMPD, V346, P184, DOI 10.1016/S0925-8388(02)00517-0 Schlapbach L, 2001, NATURE, V414, P353, DOI 10.1038/35104634 Ronnebro E, 2000, J ALLOY COMPD, V299, P101, DOI 10.1016/S0925-8388(99)00665-9 Zaluski L, 1999, J ALLOY COMPD, V290, P71, DOI 10.1016/S0925-8388(99)00211-X Bogdanovic B, 1997, J ALLOY COMPD, V253, P1, DOI 10.1016/S0925-8388(96)03049-6 Perdew JP, 1996, PHYS REV LETT, V77, P3865, DOI 10.1103/PhysRevLett.77.3865 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 PERDEW JP, 1991, PHYS REV LETT, V66, P508, DOI 10.1103/PhysRevLett.66.508 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 IHM J, 1979, J PHYS C SOLID STATE, V12, P4409, DOI 10.1088/0022-3719/12/21/009 HOHENBERG P, 1965, PHYS REV A, V140, P1133 SANDROCK G, 17 IEAMa, Zhu Chou, M. Y.US Department of Energy (DOE)[DE-FG02-05ER46229]This work is supported by the US Department of Energy (DOE) under Grant No. DE-FG02-05ER46229. Calculational resources at the National Energy Research Scientific Computing Center (NERSC) are acknowledged.ELSEVIER SCIENCE SALAUSANNE

Abstract:

Accurate multideterminant ground-state energies of circular quantum dots containing N <= 13 electrons as a function of interaction strength have been evaluated by the diffusion quantum Monte Carlo method. Two unique features are found for these confined two-dimensional systems: (1) as the electron density decreases, the quantum dots favor states with zero orbital angular momentum (L = 0); and (2) for some values of N, the ground state cannot be fully spin-polarized because of a symmetry constraint.

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ISI Document Delivery No.: 466XUTimes Cited: 6Cited Reference Count: 31Cited References: Guclu AD, 2008, PHYS REV B, V77, DOI 10.1103/PhysRevB.77.041301 Ghosal A, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.085341 Ghosal A, 2006, NAT PHYS, V2, P336, DOI 10.1038/nphys293 Weiss S, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.245301 Yannouleas C, 2004, PHYS REV B, V70, DOI 10.1103/PhysRevB.70.235319 Yannouleas C, 2004, PHYS REV B, V69, DOI 10.1103/PhysRevB.69.113306 Reusch B, 2003, EUROPHYS LETT, V64, P84, DOI 10.1209/epl/i2003-00137-2 Yannouleas C, 2003, PHYS REV B, V68, DOI 10.1103/PhysRevB.68.035325 Yannouleas C, 2003, PHYS REV B, V68, DOI 10.1103/PhysRevB.68.035326 Mikhailov SA, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.153313 Reimann SM, 2002, REV MOD PHYS, V74, P1283, DOI 10.1103/RevModPhys.74.1283 Yannouleas C, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.115315 Filinov AV, 2001, PHYS REV LETT, V86, P3851, DOI 10.1103/PhysRevLett.86.3851 Bernu B, 2001, PHYS REV LETT, V86, P870, DOI 10.1103/PhysRevLett.86.870 Pederiva F, 2000, PHYS REV B, V62, P8120, DOI 10.1103/PhysRevB.62.8120 Reimann SM, 2000, PHYS REV B, V62, P8108, DOI 10.1103/PhysRevB.62.8108 Egger R, 1999, PHYS REV LETT, V83, P462, DOI 10.1103/PhysRevLett.83.462 Yannouleas C, 1999, PHYS REV LETT, V82, P5325, DOI 10.1103/PhysRevLett.82.5325 Egger R, 1999, PHYS REV LETT, V82, P3320, DOI 10.1103/PhysRevLett.82.3320 Kouwenhoven LP, 1997, SCIENCE, V278, P1788, DOI 10.1126/science.278.5344.1788 Muller HM, 1996, PHYS REV B, V54, P14532, DOI 10.1103/PhysRevB.54.14532 Ashoori RC, 1996, NATURE, V379, P413, DOI 10.1038/379413a0 JAIN JK, 1995, EUROPHYS LETT, V29, P321, DOI 10.1209/0295-5075/29/4/009 FERCONI M, 1994, PHYS REV B, V50, P14722, DOI 10.1103/PhysRevB.50.14722 BEDANOV VM, 1994, PHYS REV B, V49, P2667, DOI 10.1103/PhysRevB.49.2667 KASTNER MA, 1993, PHYS TODAY, V46, P24, DOI 10.1063/1.881393 KASTNER MA, 1992, REV MOD PHYS, V64, P849, DOI 10.1103/RevModPhys.64.849 ASHOORI RC, 1992, PHYS REV LETT, V68, P3088, DOI 10.1103/PhysRevLett.68.3088 MEIRAV U, 1990, PHYS REV LETT, V65, P771, DOI 10.1103/PhysRevLett.65.771 JAIN JK, 1989, PHYS REV LETT, V63, P199, DOI 10.1103/PhysRevLett.63.199 LAUGHLIN RB, 1983, PHYS REV LETT, V50, P1395, DOI 10.1103/PhysRevLett.50.1395Zeng, Lang Geist, W. Ruan, W. Y. Umrigar, C. J. Chou, M. Y.U.S. Department of Energy[DE-FG0297ER45632]; National Science Foundation[DMR-02-05328]; National Energy Research Scientific Computing Center (NERSC)``We thank Constantine Yannouleas and Uzi Landman for helpful discussions. This work is supported in part by the U.S. Department of Energy under Grant No. DE-FG0297ER45632, the National Science Foundation under Grant No. DMR-02-05328, and the National Energy Research Scientific Computing Center (NERSC)AMER PHYSICAL SOCCOLLEGE PK

Abstract:

The physical and chemical properties of thin metal films show damped oscillations as a function of film thickness (one-dimensional shell effects). While the oscillation period, determined by subband crossings of the Fermi level, is the same for all properties, the phases can be different. Specifically, oscillations in the work function and surface energy are offset by 1/4 of a period. For Pb(111) films, this offset is similar to 0.18 monolayers, a seemingly very small effect. However, aliasing caused by the discrete atomic layer structure leads to striking out-of-phase beating patterns displayed by these two quantities.

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ISI Document Delivery No.: 457ZITimes Cited: 11Cited Reference Count: 25Cited References: Ozer MM, 2007, SCIENCE, V316, P1594, DOI 10.1126/science.1142159 Ma XC, 2007, P NATL ACAD SCI USA, V104, P9204, DOI 10.1073/pnas.0611024104 Tringides MC, 2007, PHYS TODAY, V60, P50, DOI 10.1063/1.2731973 Eom D, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.027005 Czoschke P, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.075402 Chiang TC, 2004, SCIENCE, V306, P1900, DOI 10.1126/science.1106675 Guo Y, 2004, SCIENCE, V306, P1915, DOI 10.1126/science.1105130 Czoschke P, 2004, PHYS REV LETT, V93, DOI 10.1103/PhysRevLett.93.036103 HARRIS FJ, 2004, MULTIRATE SIGNAL PRO, P23402 Wei CM, 2003, PHYS REV B, V68, DOI 10.1103/PhysRevB.68.125406 Paggel JJ, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.233403 Wu YZ, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.245418 Mans A, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.195410 Luh DA, 2002, PHYS REV LETT, V88, DOI 10.1103/PhysRevLett.88.256802 Matsuda I, 2002, PHYS REV B, V65, DOI 10.1103/PhysRevB.65.085327 Milun M, 2002, REP PROG PHYS, V65, P99, DOI 10.1088/0034-4885/65/2/201 Aballe L, 2001, PHYS REV LETT, V87, DOI 10.1103/PhysRevLett.87.156801 Luh DA, 2001, SCIENCE, V292, P1131, DOI 10.1126/science.292.5519.1131 Chiang TC, 2000, SURF SCI REP, V39, P181, DOI 10.1016/S0167-5729(00)00006-6 LINDGREN SA, 2000, HDB SURFACE SCI, V2, P23402 Himpsel FJ, 1998, ADV PHYS, V47, P511, DOI 10.1080/000187398243519 PRESS WH, 1992, NUMERICAL RECIPES FO, P23402 TRIVEDI N, 1988, PHYS REV B, V38, P12298, DOI 10.1103/PhysRevB.38.12298 SCHULTE FK, 1976, SURF SCI, V55, P427, DOI 10.1016/0039-6028(76)90250-8 BLATT JM, 1963, PHYS REV LETT, V10, P332, DOI 10.1103/PhysRevLett.10.332Miller, T. Chou, M. Y. Chiang, T. -C.U. S. Department of Energy[FG02-07ER46383, DE-FG02-97ER45632]; ACS Petroleum Research Fund; U. S. National Science Foundation[DMR-0503323, DMR-05-37588]This work is supported by the U. S. Department of Energy ( Grant No. DE-FG02-07ER46383 for T.-C. C. and Grant No. DE-FG02-97ER45632 for M. Y. C.). We acknowledge the ACS Petroleum Research Fund and the U. S. National Science Foundation ( Grant No. DMR-0503323) for partial support of the equipment and personnel at the Synchrotron Radiation Center ( SRC). The SRC is supported by the U. S. National Science Foundation ( Grant No. DMR-05-37588). We acknowledge helpful discussions with C. Ken Shih.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

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Notes:

ISI Document Delivery No.: V16HYTimes Cited: 0Cited Reference Count: 0Chiang, Tai C. Chou, Mei-YinAMER CHEMICAL SOCWASHINGTON

Abstract:

We have systematically investigated the effect of oxidation on the structural and electronic properties of graphene based on first-principles calculations. Energetically favorable atomic configurations and building blocks are identified, which contain epoxide and hydroxyl groups in close proximity with each other. Different arrangements of these units yield a local-density approximation band gap over a range of a few eV. These results suggest the possibility of creating and tuning the band gap in graphene by varying the oxidation level and the relative amount of epoxide and hydroxyl functional groups on the surface.

Notes:

ISI Document Delivery No.: 487PYTimes Cited: 39Cited Reference Count: 27Cited References: Elias DC, 2009, SCIENCE, V323, P610 Jung I, 2008, NANO LETT, V8, P4283, DOI 10.1021/nl8019938 Cai WW, 2008, SCIENCE, V321, P1815, DOI 10.1126/science.1162369 Boukhvalov DW, 2008, J AM CHEM SOC, V130, P10697, DOI 10.1021/ja8021686 Wu XS, 2008, PHYS REV LETT, V101 Eda G, 2008, NAT NANOTECHNOL, V3, P270, DOI 10.1038/nnano.2008.83 Pandey D, 2008, SURF SCI, V602, P1607, DOI 10.1016/j.susc.2008.02.025 Li XL, 2008, SCIENCE, V319, P1229, DOI 10.1126/science.1150878 Li D, 2008, NAT NANOTECHNOL, V3, P101, DOI 10.1038/nnano.2007.451 Kudin KN, 2008, NANO LETT, V8, P36, DOI 10.1021/nl071822y Gilje S, 2007, NANO LETT, V7, P3394, DOI 10.1021/nl0717715 Gomez-Navarro C, 2007, NANO LETT, V7, P3499, DOI 10.1021/nl072090c Giovannetti G, 2007, PHYS REV B, V76 de Heer WA, 2007, SOLID STATE COMMUN, V143, P92, DOI 10.1016/j.ssc.2007.04.023 Stankovich S, 2007, CARBON, V45, P1558, DOI 10.1016/j.carbon.2007.02.034 Han MY, 2007, PHYS REV LETT, V98 Geim AK, 2007, NAT MATER, V6, P183, DOI 10.1038/nmat1849 Ohta T, 2006, SCIENCE, V313, P951, DOI 10.1126/science.1130681 Li JL, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.176101 Schniepp HC, 2006, J PHYS CHEM B, V110, P8535, DOI 10.1021/jp060936f Lerf A, 1998, J PHYS CHEM B, V102, P4477, DOI 10.1021/jp9731821 He HY, 1998, CHEM PHYS LETT, V287, P53, DOI 10.1016/S0009-2614(98)00144-4 NAKAJIMA T, 1994, CARBON, V32, P469, DOI 10.1016/0008-6223(94)90168-6 KRESSE G, 1993, PHYS REV B, V47, P558, DOI 10.1103/PhysRevB.47.558 MERMOUX M, 1991, CARBON, V29, P469, DOI 10.1016/0008-6223(91)90216-6 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 NAKAJIMA T, 1988, CARBON, V26, P357, DOI 10.1016/0008-6223(88)90227-8Yan, Jia-An Xian, Lede Chou, M. Y.Department of Energy[DE-FG02-97ER45632]; National Science Foundation[DMR-08-20382]; Office of Science of the U. S. Department of Energy[DE-AC02-05CH11231]We acknowledge stimulating discussions with W. de Heer, C. Berger, X. Wu, and M. Sprinkle. J. A. Y. thanks D. Pandey for sending a copy of their paper. This work is supported by the Department of Energy (Grant No. DEFG02-97ER45632). L. X. acknowledges support from the Georgia Tech MRSEC funded by the National Science Foundation (Grant No. DMR-08-20382). This research used computational resources at the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231, and the National Science Foundation TeraGrid resources provided by the Texas Advanced Computing Center (TACC).AMER PHYSICAL SOCCOLLEGE PK

Abstract:

n/a

Notes:

ISI Document Delivery No.: V16HYTimes Cited: 0Cited Reference Count: 0Yan, Jia-An Xian, Lede Chou, Mei-YinAMER CHEMICAL SOCWASHINGTON

2008

Abstract:

The Li-Mg-N-H system has been identified as a promising hydrogen storage material due to its moderate operation conditions as well as the high capacity and reversibility. Recently Rijssenbeek et al. [J. Alloys Compd. 454, 233 (2008)] reported that Li(2)Mg(NH)(2) has disordered cation and vacancy arrangements at room temperature and above. We present our first-principles calculations to investigate a series of ordered low-energy configurations for this compound. Specific local orderings are found in the cation-vacancy arrangement, shedding light on the experimental disordered structure models. A possible ordered phase at low temperature is proposed based on these local orderings. Reaction energetics and phase stability are further discussed. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.3003067]

Notes:

ISI Document Delivery No.: 367SGTimes Cited: 2Cited Reference Count: 36Cited References: Rijssenbeek J, 2008, J ALLOY COMPD, V454, P233, DOI 10.1016/j.jallcom.2006.12.008 Wang Y, 2007, PHYS REV B, V76 Yang J, 2007, J ALLOY COMPD, V430, P334, DOI 10.1016/j.jallcom.2006.05.039 Sorby MH, 2007, J ALLOY COMPD, V428, P297, DOI 10.1016/j.jallcom.2006.03.037 Balogh MP, 2006, J ALLOY COMPD, V420, P326, DOI 10.1016/j.jallcom.2005.11.018 Leng H, 2006, J PHYS CHEM B, V110, P12964, DOI 10.1021/jp061120h Xiong ZT, 2006, J ALLOY COMPD, V417, P190, DOI 10.1016/j.jallcom.2005.07.072 Magyari-Kope B, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.220101 Alapati SV, 2006, J PHYS CHEM B, V110, P8769, DOI 10.1021/jp060482m Luo WF, 2006, J ALLOY COMPD, V407, P274, DOI 10.1016/j.jallcom.2005.06.046 Luo W, 2005, J ALLOY COMPD, V404, P392, DOI 10.1016/j.jallcom.2005.01.131 Herbst JF, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.125120 Ichikawa T, 2005, J ALLOY COMPD, V400, P245, DOI 10.1016/j.jallcom.2005.03.068 Xiong ZT, 2005, J ALLOY COMPD, V398, P235, DOI 10.1016/j.jallcom.2005.02.010 Xiong ZT, 2005, J ALLOY COMPD, V395, P209, DOI 10.1016/j.jallcom.2004.10.062 Pinkerton FE, 2005, J PHYS CHEM B, V109, P6, DOI 10.1021/jp0455475 Nakamori Y, 2005, APPL PHYS A-MATER, V80, P1, DOI 10.1007/s00339-004-3002-6 Nakamori Y, 2004, J POWER SOURCES, V138, P309, DOI 10.1016/j.jpowsour.2004.06.026 Luo WF, 2004, J ALLOY COMPD, V381, P284, DOI 10.1016/j.jallcom.2004.03.119 Nakamori Y, 2004, J ALLOY COMPD, V377, pL1, DOI 10.1016/j.jallcom.2004.01.038 Xiong ZT, 2004, ADV MATER, V16, P1522, DOI 10.1002/adma.200400571 Leng HY, 2004, J PHYS CHEM B, V108, P8763, DOI 10.1021/jp048002j Nakamori Y, 2004, J ALLOY COMPD, V370, P271, DOI 10.1016/j.jallcom.2003.08.089 Nakamori Y, 2004, MAT SCI ENG B-SOLID, V108, P48, DOI 10.1016/j.mseb.2003.10.044 Ichikawa T, 2004, J ALLOY COMPD, V365, P271, DOI 10.1016/S0925-8388(03)00637-6 Chen P, 2003, J PHYS CHEM B, V107, P10967, DOI 10.1021/jp034149j Xiong ZT, 2003, J MATER CHEM, V13, P1676, DOI 10.1039/b211563h Chen P, 2002, NATURE, V420, P302, DOI 10.1038/nature01210 Perdew JP, 1996, PHYS REV LETT, V77, P3865, DOI 10.1103/PhysRevLett.77.3865 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 BLOCHL PE, 1994, PHYS REV B, V50, P17953, DOI 10.1103/PhysRevB.50.17953 IHM J, 1979, J PHYS C SOLID STATE, V12, P4409, DOI 10.1088/0022-3719/12/21/009 SHANNON RD, 1976, THEOR GEN CRYSTALLOG, V32, P751 KOHN W, 1965, PHYS REV, V140, P1133 HOHENBERG P, 1964, PHYS REV B, V136, pB864, DOI 10.1103/PhysRev.136.B864Ma, Zhu Chou, M. Y.US Department of Energy[DE-FG02-05ER46229]We are grateful to Job Rijssenbeek for the stimulation discussions. Discussions with Dr. Yan Wang are also acknowledged. This work is supported by the US Department of Energy (DOE) under Grant No. DE-FG02-05ER46229. Computational resources at the National Energy Research Scientific Computing Center (NERSC) are acknowledged.AMER INST PHYSICSMELVILLE

Abstract:

Using first-principles calculations within density functional theory, we have investigated the electronic properties of H-passivated Si nanowires (SiNWs) oriented along the 112 direction, with the atomic geometries retrieved via global search using genetic algorithm. We show that [112] SiNWs have an indirect band gap in the ultrathin diameter regime, whereas the energy difference between the direct and indirect fundamental band gaps progressively decreases as the wire size increases, indicating that larger [112] SiNWs could have a quasi-direct band gap. We further show that this quasi-direct gap feature can be enhanced when applying uniaxial compressive stress along the wire axis. Moreover, our calculated results also reveal that the electronic band structure is sensitive to the change of the aspect ratio of the cross sections.

Notes:

ISI Document Delivery No.: 356DYTimes Cited: 8Cited Reference Count: 30Cited References: LU AJ, 2008, NANOTECHNOLOGY, V9, P35708 Ng MF, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.155435 Rurali R, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.113303 Yan JA, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.115319 Lu N, 2007, J PHYS CHEM C, V111, P7933, DOI 10.1021/jp072519o Goldberger J, 2006, NANO LETT, V6, P973, DOI 10.1021/nl060166j Niquet YM, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.165319 Chan TL, 2006, NANO LETT, V6, P277, DOI 10.1021/nl0522633 LI J, 2006, PHYS REV B, V74, P75333 PONOMAREVA L, 2006, PHYS REV B, V74 VO T, 2006, PHYS REV B, V74, P45116 Koo SM, 2005, NANO LETT, V5, P2519, DOI 10.1021/nl051855i Migas DB, 2005, J APPL PHYS, V98, DOI 10.1063/1.2039275 RURALI R, 2005, PHYS REV LETT, V94, P26805 Zhao XY, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.236805 Hahm J, 2004, NANO LETT, V4, P51, DOI 10.1021/nl034853b Ma DDD, 2003, SCIENCE, V299, P1874, DOI 10.1126/science.1080313 Cui Y, 2003, NANO LETT, V3, P149, DOI 10.1021/nl025875l Williamson AJ, 2002, PHYS REV LETT, V89, DOI 10.1103/PhysRevLett.89.196803 Cui Y, 2001, SCIENCE, V293, P1289, DOI 10.1126/science.1062711 Cui Y, 2001, SCIENCE, V291, P851, DOI 10.1126/science.291.5505.851 Ho KM, 1998, NATURE, V392, P582 PIMPINELLI A, 1998, PHYS CRYSTAL GROWTH, pCH3 KRESSE G, 1994, J PHYS-CONDENS MAT, V6, P8245, DOI 10.1088/0953-8984/6/40/015 KRESSE G, 1994, PHYS REV B, V49, P14251, DOI 10.1103/PhysRevB.49.14251 KRESSE G, 1994, J COMPUT MAT SCI, V6, P15 DELERUE C, 1993, PHYS REV B, V48, P11024, DOI 10.1103/PhysRevB.48.11024 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 HYBERTSEN MS, 1986, PHYS REV B, V34, P5390, DOI 10.1103/PhysRevB.34.5390 MONKHORST HJ, 1976, PHYS REV B, V13, P5188, DOI 10.1103/PhysRevB.13.5188Huang, Li Lu, Ning Yan, Jia-An Chou, M. Y. Wang, Cai-Zhuang Ho, Kai-MingU.S. Department of Energy by Iowa State University[DE-AC02-07CH11358]; National Science Foundation[DMR-02-05328]; Department of Energy[DE-FG02-97ER45632, DE-AC03-76SF00098]; National Energy Research Supercomputing Center (NERSC); San Diego Supercomputer Center (SDSC)Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. This work was also supported by the National Science Foundation (Grant No. DMR-02-05328) and the Department of Energy (Grant No. DE-FG02-97ER45632 and Computational Materials Science Network). The computation used resources of the National Energy Research Supercomputing Center (NERSC), which is supported by the Department of Energy (Grant No. DE-AC03-76SF00098), and the San Diego Supercomputer Center (SDSC).AMER CHEMICAL SOCWASHINGTON

Abstract:

The electronic structure of Si/Ge core-shell nanowires along the [110] and [111] directions are studied with first-principles calculations. We identify the near-gap electronic states that are spatially separated within the core or the shell region, making it possible for a dopant to generate carriers in a different region. The confinement energies of these core and shell states provide an operational definition of the "band offset," which is not only size dependent but also component dependent. The optimal doping strategy in Si/Ge core-shell nanowires is proposed based on these energy results.

Notes:

ISI Document Delivery No.: 316TCTimes Cited: 24Cited Reference Count: 24Cited References: Yan JA, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.115319 Bruno M, 2007, PHYS REV LETT, V98 Vo T, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.045116 Xiang J, 2006, NATURE, V441, P489, DOI 10.1038/nature04796 Bruno M, 2005, PHYS REV B, V72, DOI 10.1103/PhysRevB.72.153310 Noborisaka J, 2005, APPL PHYS LETT, V87, DOI 10.1063/1.2035332 Lu W, 2005, P NATL ACAD SCI USA, V102, P10046, DOI 10.1073/pnas.0504581102 Glazov MM, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.155313 Musin RN, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.155318 Rurali R, 2005, PHYS REV LETT, V94, DOI 10.1103/PhysRevLett.94.026805 Zhao XY, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.236805 Greytak AB, 2004, APPL PHYS LETT, V84, P4176, DOI 10.1063/1.1755846 Cui Y, 2003, NANO LETT, V3, P149, DOI 10.1021/nl025875l Lauhon LJ, 2002, NATURE, V420, P57, DOI 10.1038/nature01141 Bjork MT, 2002, APPL PHYS LETT, V80, P1058 Gudiksen MS, 2002, NATURE, V415, P617, DOI 10.1038/415617a Duan XF, 2001, NATURE, V409, P66, DOI 10.1038/35051047 Chang CL, 1998, APPL PHYS LETT, V73, P3568, DOI 10.1063/1.122809 Schaffler F, 1997, SEMICOND SCI TECH, V12, P1515, DOI 10.1088/0268-1242/12/12/001 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 TSERBAK C, 1995, SEMICOND SCI TECH, V10, P1604, DOI 10.1088/0268-1242/10/12/008 HYBERTSEN MS, 1986, PHYS REV B, V34, P5390, DOI 10.1103/PhysRevB.34.5390 VANDEWALLE CG, 1986, PHYS REV B, V34, P5621, DOI 10.1103/PhysRevB.34.5621Yang, Li Musin, Ryza N. Wang, Xiao-Qian Chou, M. Y.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

The phonon dispersions of monolayer and few-layer graphene (AB bilayer, and ABA and ABC trilayers) are investigated using the density-functional perturbation theory. Compared with the monolayer, the optical phonon E(2g) mode at Gamma splits into two and three doubly degenerate branches for bilayer and trilayer graphene, respectively, due to the weak interlayer coupling. These modes are of various symmetries and exhibit different sensitivities to either Raman or infrared measurements (or both). The splitting is found to be 5 cm(-1) for bilayer and 2-5 cm(-1) for trilayer graphene. The interlayer coupling is estimated to be about 2 cm(-1). We found that the highest optical modes at K move up by about 12 cm(-1) for bilayer and 18 cm(-1) for trilayer relative to monolayer graphene. The atomic displacements of these optical eigenmodes are analyzed.

Notes:

ISI Document Delivery No.: 282BQTimes Cited: 19Cited Reference Count: 50Cited References: de Heer WA, 2007, SOLID STATE COMMUN, V143, P92, DOI 10.1016/j.ssc.2007.04.023 Ferrari AC, 2007, SOLID STATE COMMUN, V143, P47, DOI 10.1016/j.ssc.2007.03.052 Mohr M, 2007, PHYS REV B, V76, DOI 10.1103/PhysRevB.76.035439 Hass J, 2007, PHYS REV B, V75 Yan J, 2007, PHYS REV LETT, V98 Geim AK, 2007, NAT MATER, V6, P183, DOI 10.1038/nmat1849 Graf D, 2007, NANO LETT, V7, P238, DOI 10.1021/nl061702a Bostwick A, 2007, NAT PHYS, V3, P36, DOI 10.1038/nphys477 Katsnelson MI, 2007, MATER TODAY, V10, P20, DOI 10.1016/S1369-7021(06)71788-6 Piscanec S, 2007, PHYS REV B, V75 Lazzeri M, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.266407 Gupta A, 2006, NANO LETT, V6, P2667, DOI 10.1021/nl061420a Ferrari AC, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.187401 Dappe YJ, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.205434 Latil S, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.036803 Berger C, 2006, SCIENCE, V312, P1191, DOI 10.1126/science.1125925 Chakarova-Kack SD, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.146107 Ooi N, 2006, CARBON, V44, P231, DOI 10.1016/j.carbon.2005.07.036 ANDO T, 2006, PHYS SOC JPN, V75, P24701 Lazzeri M, 2005, PHYS REV LETT, V95, DOI 10.1103/PhysRevLett.95.236802 Novoselov KS, 2005, NATURE, V438, P197, DOI 10.1038/nature04233 Zhang YB, 2005, NATURE, V438, P201, DOI 10.1038/nature04235 Mounet N, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.205214 Berger C, 2004, J PHYS CHEM B, V108, P19912, DOI 10.1021/jp040650f Piscanec S, 2004, PHYS REV LETT, V93, DOI 10.1103/PhysRevLett.93.185503 Jiang J, 2004, CHEM PHYS LETT, V392, P383, DOI 10.1016/j.cplett.2004.05.097 Wirtz L, 2004, SOLID STATE COMMUN, V131, P141, DOI 10.1016/j.ssc.2004.04.042 Maultzsch J, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.075501 Rydberg H, 2003, PHYS REV LETT, V91, DOI 10.1103/PhysRevLett.91.126402 Dubay O, 2003, PHYS REV B, V67, DOI 10.1103/PhysRevB.67.035401 Gruneis A, 2002, PHYS REV B, V65, DOI 10.1103/PhysRevB.65.155405 Girifalco LA, 2002, PHYS REV B, V65, DOI 10.1103/PhysRevB.65.125404 Zabel H, 2001, J PHYS-CONDENS MAT, V13, P7679, DOI 10.1088/0953-8984/13/34/313 Baroni S, 2001, REV MOD PHYS, V73, P515, DOI 10.1103/RevModPhys.73.515 Yao Z, 2000, PHYS REV LETT, V84, P2941, DOI 10.1103/PhysRevLett.84.2941 Kohn W, 1998, PHYS REV LETT, V80, P4153, DOI 10.1103/PhysRevLett.80.4153 Siebentritt S, 1997, PHYS REV B, V55, P7927, DOI 10.1103/PhysRevB.55.7927 BRILLSON LJ, 1997, PHYS SEMIMETALS NARR, P187 MERCER JL, 1994, PHYS REV B, V49, P8506, DOI 10.1103/PhysRevB.49.8506 TROULLIER N, 1993, PHYS REV B, V43, P1991 METHFESSEL M, 1989, PHYS REV B, V40, P3616, DOI 10.1103/PhysRevB.40.3616 CHADI DJ, 1989, ATOMISTIC SIMULATION, P309 OSHIMA C, 1988, SOLID STATE COMMUN, V65, P1601, DOI 10.1016/0038-1098(88)90660-6 NEMANICH RJ, 1979, PHYS REV B, V20, P392, DOI 10.1103/PhysRevB.20.392 NICKLOW R, 1972, PHYS REV B, V5, P4951, DOI 10.1103/PhysRevB.5.4951 FRIEDEL RA, 1971, J PHYS CHEM-US, V75, P1149, DOI 10.1021/j100678a021 TOUINSTRA F, 1970, J CHEM PHYS, V53, P1129 WYCKOFF RWG, 1963, CRYSTAL STRUCTURE, V1 KOHN W, 1959, PHYS REV LETT, V2, P393, DOI 10.1103/PhysRevLett.2.393 LIFSHITS IM, 1952, ZH EKSP TEOR FIZ+, V22, P475Yan, Jia-An Ruan, W. Y. Chou, M. Y.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

Aluminum hydride (alane) AlH(3) is an important material in hydrogen storage applications. It is known that AlH(3) exists in multiply forms of polymorphs, where alpha-AlH(3) is found to be the most stable with a hexagonal structure. Recent experimental studies on gamma-AlH(3) reported an orthorhombic structure with a unique double-bridge bond between certain Al and H atoms. This was not found in alpha-AlH(3) or other polymorphs. Using density functional theory, we have investigated the energetics, and the structural, electronic, and phonon vibrational properties for the newly reported gamma-AlH(3) structure. The current calculation concludes that gamma-AlH(3) is less stable than alpha-AlH(3) by 1.2 KJ/mol, with the zero-point energy included. Interesting binding features associated with the unique geometry of gamma-AlH(3) are discussed from the calculated electronic properties and phonon vibrational modes. The binding of H-s with higher energy Al-p,d orbitals is enhanced within the double-bridge arrangement, giving rise to a higher electronic energy for the system. Distinguishable new features in the vibrational spectrum of gamma-AlH(3) were attributed to the double-bridge and hexagonal-ring structures.

Notes:

ISI Document Delivery No.: 258ISTimes Cited: 9Cited Reference Count: 25Cited References: Brinks HW, 2007, J ALLOY COMPD, V441, P364, DOI 10.1016/j.jallcom.2006.09.139 Yartys VA, 2007, INORG CHEM, V46, P1051, DOI 10.1021/ic0617487 van Setten MJ, 2007, PHYS REV B, V75, DOI 10.1103/PhysRevB.75.035204 Graetz J, 2006, J ALLOY COMPD, V424, P262, DOI 10.1016/j.jallcom.2005.11.086 Graetz J, 2005, J PHYS CHEM B, V109, P22181, DOI 10.1021/jp0546960 Ke XZ, 2005, PHYS REV B, V71, DOI 10.1103/PhysRevB.71.184107 SANDROCK G, 2005, J APPL PHYS A, V80, P687 Wolverton C, 2004, PHYS REV B, V69, DOI 10.1103/PhysRevB.69.144109 Baroni S, 2001, REV MOD PHYS, V73, P515, DOI 10.1103/RevModPhys.73.515 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 PERDEW JP, 1992, PHYS REV B, V46, P6671, DOI 10.1103/PhysRevB.46.6671 VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 BARANOWSKI B, 1983, Z PHYS CHEM NEUE FOL, V135, P27 HERLEY PJ, 1981, J PHYS CHEM-US, V85, P1887, DOI 10.1021/j150613a022 HERLEY PJ, 1981, J PHYS CHEM-US, V85, P1874, DOI 10.1021/j150613a020 HERLEY PJ, 1981, J PHYS CHEM-US, V85, P1882, DOI 10.1021/j150613a021 HERLEY PJ, 1980, J SOLID STATE CHEM, V35, P391, DOI 10.1016/0022-4596(80)90537-X HERLEY PJ, 1978, J PHYS CHEM SOLIDS, V39, P1013, DOI 10.1016/0022-3697(78)90119-1 BROWER FM, 1976, J AM CHEM SOC, V98, P2450, DOI 10.1021/ja00425a011 MONKHORST HJ, 1976, PHYS REV B, V13, P5188, DOI 10.1103/PhysRevB.13.5188 TURLEY JW, 1969, INORG CHEM, V8, P18, DOI 10.1021/ic50071a005 SINKE GC, 1967, J CHEM PHYS, V47, P2759, DOI 10.1063/1.1712294 KOHN W, 1965, PHYS REV, V140, P1133 HOHENBERG P, 1964, PHYS REV B, V136, pB864, DOI 10.1103/PhysRev.136.B864Wang, Yan Yan, Jia-An Chou, M. Y.AMER PHYSICAL SOCCOLLEGE PK

2007

Abstract:

By using first-principles pseudopotential methods, we have studied the electronic properties of hydrogen-passivated silicon nanowires along the [100], [110], and [111] directions with diameter up to 3.4 nm. It is found that as the diameter decreases, the energy band gaps are distinctly enlarged due to the confinement effect. The valence-band maximum moves down while the conduction-band minimum moves up compared with the bulk. By using the many-body perturbation theory within the GW approximation, we have also investigated the self-energy correction to the energy band gaps. Our calculational results show that, although the band gap values strongly depend on both the diameter and orientation, the GW corrections are mainly dependent on diameter and less sensitive to the growth orientation. The effective mass as a function of diameter is also discussed.

Notes:

ISI Document Delivery No.: 215CRTimes Cited: 40Cited Reference Count: 37Cited References: Bruno M, 2007, PHYS REV LETT, V98 Cao JX, 2006, PHYS REV LETT, V97, DOI 10.1103/PhysRevLett.97.136105 Li J, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.075333 Vo T, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.045116 Rozzi CA, 2006, PHYS REV B, V73, DOI 10.1103/PhysRevB.73.205119 Sirbuly DJ, 2005, J PHYS CHEM B, V109, P15190, DOI 10.1021/jp051813i Wang J, 2005, IEEE T ELECTRON DEV, V52, P1589, DOI 10.1109/TED.2005.850945 Friedman RS, 2005, NATURE, V434, P1085, DOI 10.1038/4341085a Wang J, 2005, APPL PHYS LETT, V86, DOI 10.1063/1.1873055 Rurali R, 2005, PHYS REV LETT, V94, DOI 10.1103/PhysRevLett.94.026805 Zhao XY, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.236805 Spataru CD, 2004, APPL PHYS A-MATER, V78, P1129, DOI 10.1007/s00339-003-2464-2 Wu Y, 2004, NANO LETT, V4, P433, DOI 10.1021/nl035162i Ma DDD, 2003, SCIENCE, V299, P1874, DOI 10.1126/science.1080313 Cui Y, 2003, NANO LETT, V3, P149, DOI 10.1021/nl025875l Katz D, 2002, PHYS REV LETT, V89 Huang Y, 2001, SCIENCE, V294, P1313, DOI 10.1126/science.1066192 Cui Y, 2001, SCIENCE, V293, P1289, DOI 10.1126/science.1062711 Huang MH, 2001, SCIENCE, V292, P1897, DOI 10.1126/science.1060367 Cui Y, 2001, APPL PHYS LETT, V78, P2214, DOI 10.1063/1.1363692 Cui Y, 2001, SCIENCE, V291, P851, DOI 10.1126/science.291.5505.851 Duan XF, 2001, NATURE, V409, P66, DOI 10.1038/35051047 Rohlfing M, 2000, PHYS REV B, V62, P4927, DOI 10.1103/PhysRevB.62.4927 Duan XF, 2000, APPL PHYS LETT, V76, P1116, DOI 10.1063/1.125956 HOLMES JD, 2000, SCIENCE, V287, P1472 Morales AM, 1998, SCIENCE, V279, P208, DOI 10.1126/science.279.5348.208 DELLEY B, 1995, APPL PHYS LETT, V67, P2370, DOI 10.1063/1.114348 ONIDA G, 1995, PHYS REV LETT, V75, P818, DOI 10.1103/PhysRevLett.75.818 YEH CY, 1994, PHYS REV B, V50, P14405, DOI 10.1103/PhysRevB.50.14405 DELERUE C, 1993, PHYS REV B, V48, P11024, DOI 10.1103/PhysRevB.48.11024 HYBERTSEN MS, 1993, PHYS REV B, V48, P4608, DOI 10.1103/PhysRevB.48.4608 BUDA F, 1992, PHYS REV LETT, V69, P1272, DOI 10.1103/PhysRevLett.69.1272 READ AJ, 1992, PHYS REV LETT, V69, P1232, DOI 10.1103/PhysRevLett.69.1232 TROULLIER N, 1991, PHYS REV B, V43, P1993, DOI 10.1103/PhysRevB.43.1993 CANHAM LT, 1990, APPL PHYS LETT, V57, P1046, DOI 10.1063/1.103561 HYBERTSEN MS, 1986, PHYS REV B, V34, P5390, DOI 10.1103/PhysRevB.34.5390 DILLON JA, 1958, J APPL PHYS, V29, P1195, DOI 10.1063/1.1723401Yan, Jia-An Yang, Li Chou, M. Y.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

Hydrogenation of the inten-netallic compound LaMg2Pd at 200 degrees C and 10 bar leads to a complex metal hydride of composition LaMg2PdH7. Its structure has orthorhombic symmetry and displays tetrahedral [PdH4](4-) anions. The Pd-H bond distances as measured on the deuteride range from 1.71 to 1.78 angstrom and the H-Pd-H bond angles from 95 degrees to 122 degrees. Three additional hydride anions H- occupy La2Mg2-type interstices having tetrahedral metal configurations. Band structure calculations suggest the hydride to be non-metallic and to have a band gap of similar to 1.0ev. The compound desorbs hydrogen at 125 degrees C yielding a pressure of more than I bar absolute. (C) 2006 Elsevier B.V. All rights reserved.

Notes:

ISI Document Delivery No.: 229RWTimes Cited: 5Cited Reference Count: 14Cited References: Yvon K, 2005, PHYS REV LETT, V94, DOI 10.1103/PhysRevLett.94.066403 RODRIGUEZCARVAJ.J, 2005, FULLPROF SUITE LLB S YVON K, 2005, HYDRIDES SOLID STATE, P1814 Favre-Nicolin V, 2002, J APPL CRYSTALLOGR, V35, P734, DOI 10.1107/S0021889802015236 Cerny R, 2002, J ALLOY COMPD, V340, P180, DOI 10.1016/S0925-8388(02)00050-6 Isidorsson J, 2002, APPL PHYS LETT, V80, P2305, DOI 10.1063/1.1463205 Richardson TJ, 2002, APPL PHYS LETT, V80, P1349, DOI 10.1063/1.1454218 Olofsson-Martensson M, 1999, J AM CHEM SOC, V121, P10908, DOI 10.1021/ja991047r Kresse G, 1996, COMP MATER SCI, V6, P15, DOI 10.1016/0927-0256(96)00008-0 BRONGER W, 1995, J ALLOY COMPD, V228, P119, DOI 10.1016/0925-8388(95)01670-8 KRESSE G, 1994, PHYS REV B, V49, P14251, DOI 10.1103/PhysRevB.49.14251 NOREUS D, 1988, J LESS-COMMON MET, V139, P233, DOI 10.1016/0022-5088(88)90004-5 OLOFSON M, 1988, INORG CHEM, V37, P2900 ZOLLIKER P, 1986, INORG CHEM, V25, P3590, DOI 10.1021/ic00240a012Yvon, K. Rapin, J. -Ph. Penin, N. Ma, Zhu Chou, M. Y.10th International Symposium on Metal-Hydrogen Systems, Fundamentals and ApplicationsOCT 01-06, 2006Lahaina, HIGM Res & Dev, Hawaii Hydrogen Carriers, LLC, Hy Energy, LLC, Jet Propuls Lab, NIST Ctr Neutron Res, Suzuki Shokan Co, Ltd, Toyota Motor SalesELSEVIER SCIENCE SALAUSANNESI

Abstract:

We present a first-principles study of the correlated electron-hole states in a silicon nanowire of a diameter of 1.2 nm and their influence on the optical absorption spectrum. The quasiparticle states are calculated employing a many-body Green's function approach within the GW approximation to the electron self-energy, and the effects of the electron-hole interaction to optical excitations are evaluated by solving the Bethe-Salpeter equation. The enhanced Coulomb interaction in this confined geometry results in an unusually large binding energy (1-1.5 eV) for the excitons, which dominate the optical absorption spectrum.

Notes:

ISI Document Delivery No.: 173RTTimes Cited: 20Cited Reference Count: 28Cited References: COHEN ML, 2008, ELECT STRUCTURE OPTI Bruno M, 2007, PHYS REV LETT, V98 Park CH, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.126105 Wirtz L, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.126104 Sirbuly DJ, 2005, J PHYS CHEM B, V109, P15190, DOI 10.1021/jp051813i Wang F, 2005, SCIENCE, V308, P838, DOI 10.1126/science.1110265 PALUMMO M, 2005, PHYS REV B, V72 Kholod AN, 2004, PHYS REV B, V70, DOI 10.1103/PhysRevB.70.035317 Zhao XY, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.236805 Chang E, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.196401 Spataru CD, 2004, PHYS REV LETT, V92, DOI 10.1103/PhysRevLett.92.077402 WU, 2004, NANO LETT, V4, P433 Marinopoulos AG, 2003, PHYS REV LETT, V91, DOI 10.1103/PhysRevLett.91.256402 Machon M, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.155410 Vasiliev I, 2001, PHYS REV LETT, V86, P1813, DOI 10.1103/PhysRevLett.86.1813 Cui Y, 2001, SCIENCE, V291, P851, DOI 10.1126/science.291.5505.851 Duan XF, 2001, NATURE, V409, P66, DOI 10.1038/35051047 Rohlfing M, 2000, PHYS REV B, V62, P4927, DOI 10.1103/PhysRevB.62.4927 Holmes JD, 2000, SCIENCE, V287, P1471, DOI 10.1126/science.287.5457.1471 Morales AM, 1998, SCIENCE, V279, P208, DOI 10.1126/science.279.5348.208 Ando T, 1997, J PHYS SOC JPN, V66, P1066, DOI 10.1143/JPSJ.66.1066 SANDERS GD, 1992, PHYS REV B, V45, P9202, DOI 10.1103/PhysRevB.45.9202 TROULLIER N, 1991, PHYS REV B, V43, P1993, DOI 10.1103/PhysRevB.43.1993 HYBERTSEN MS, 1986, PHYS REV B, V34, P5390, DOI 10.1103/PhysRevB.34.5390 DELCASTILLOMUSSOT M, 1985, PHYS REV B, V31, P2092, DOI 10.1103/PhysRevB.31.2092 STRINATI G, 1984, PHYS REV B, V29, P5718, DOI 10.1103/PhysRevB.29.5718 HANKE W, 1979, PHYS REV LETT, V43, P387, DOI 10.1103/PhysRevLett.43.387 KOHN W, 1965, PHYS REV, V140, P1133Yang, Li Spataru, Catalin D. Louie, Steven G. Chou, M. Y.AMER PHYSICAL SOCCOLLEGE PK

Abstract:

We report first-principles calculations of Pb (100) films up to 22 monolayers to study variations in the surface energy and work function as a function of film thickness. An even-odd oscillation is found in these two quantities, while a jelliumlike model for this s-p metal predicts a periodicity of about three monolayers. This unexpected result is explained by considering a coherent superposition of contributions from quantum-well states centered at both the Gamma and M points in the two-dimensional Brillouin zone, demonstrating the importance of crystal band structure in studying the quantum size effect in metal thin films.

Notes:

ISI Document Delivery No.: 173RSTimes Cited: 7Cited Reference Count: 29Cited References: Yu DK, 2006, PHYS REV B, V74, DOI 10.1103/PhysRevB.74.113401 Chan TL, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.226102 Binggeli N, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.036805 Eom D, 2006, PHYS REV LETT, V96, DOI 10.1103/PhysRevLett.96.027005 OZER MM, 2005, NATURE PHYS, V1, P117 Guo Y, 2004, SCIENCE, V306, P1915, DOI 10.1126/science.1105130 Aballe L, 2004, PHYS REV LETT, V93, DOI 10.1103/PhysRevLett.93.196103 Yu DK, 2004, PHYS REV B, V70, DOI 10.1103/PhysRevB.70.155417 Paggel JJ, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.233403 Wei CM, 2002, PHYS REV B, V66, DOI 10.1103/PhysRevB.66.233408 Luh DA, 2002, PHYS REV LETT, V88, DOI 10.1103/PhysRevLett.88.256802 Hupalo M, 2001, SURF SCI, V493, P526, DOI 10.1016/S0039-6028(01)01262-6 Su WB, 2001, PHYS REV LETT, V86, P5116, DOI 10.1103/PhysRevLett.86.5116 Luh DA, 2001, SCIENCE, V292, P1131, DOI 10.1126/science.292.5519.1131 Yeh V, 2000, PHYS REV LETT, V85, P5158, DOI 10.1103/PhysRevLett.85.5158 Valla T, 2000, J PHYS-CONDENS MAT, V12, pL477, DOI 10.1088/0953-8984/12/28/105 Budde K, 2000, PHYS REV B, V61, P10602 Chiang TC, 2000, SURF SCI REP, V39, P181, DOI 10.1016/S0167-5729(00)00006-6 Gavioli L, 1999, PHYS REV LETT, V82, P129, DOI 10.1103/PhysRevLett.82.129 Zhang ZY, 1998, PHYS REV LETT, V80, P5381, DOI 10.1103/PhysRevLett.80.5381 Boettger JC, 1998, J PHYS-CONDENS MAT, V10, P893, DOI 10.1088/0953-8984/10/4/017 Kresse G, 1996, PHYS REV B, V54, P11169, DOI 10.1103/PhysRevB.54.11169 Smith AR, 1996, SCIENCE, V273, P226, DOI 10.1126/science.273.5272.226 Boettger JC, 1996, PHYS REV B, V53, P13133, DOI 10.1103/PhysRevB.53.13133 SMITH NV, 1994, PHYS REV B, V49, P332, DOI 10.1103/PhysRevB.49.332 PERDEW JP, 1991, ELECT STRUCTURE SOLI VANDERBILT D, 1990, PHYS REV B, V41, P7892, DOI 10.1103/PhysRevB.41.7892 MILLER T, 1988, PHYS REV LETT, V61, P1404, DOI 10.1103/PhysRevLett.61.1404 SCHULTE FK, 1976, SURF SCI, V55, P427, DOI 10.1016/0039-6028(76)90250-8Wei, C. M. Chou, M. Y.AMERICAN PHYSICAL SOCCOLLEGE

Abstract:

Recently it was discovered that a total of 5.6 wt. % H-2 could be released from the 1:2 mixture of lithium amide and magnesium hydride at temperatures as low as 150 degrees C. With a reaction enthalpy of 44 KJ/mol H-2, this system has high potential for on-board hydrogen storage applications. The fully desorbed product is believed to be a mixed lithium and magnesium imide Li2Mg(NH)(2). In this work, the crystal structure of this mixed imide is studied from total-energy density-functional calculations. Based on a recent experimentally established space group, possible ordered configurations are examined. Important local orderings are identified for the experimentally observed disordered phase at room temperature. These unique local arrangements are also connected with the observed structural transitions above room temperature. In addition, the local ordering in Mg(NH2)(2) is analyzed. The similarity and difference of local arrangements among hydrogen, cations, and vacancies are discussed for the three amide (imide) systems: LiNH2, Mg(NH2)(2), and Li2Mg(NH)(2). The identification of the cation and hydrogen local orderings are expected to facilitate the design of new mixed imides and amides as hydrogen storage materials with desired physical properties.

Notes:

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Abstract:

We show that, if a variational parameter in the Fock-Darwin states is optimized, the lowest Landau level (LLL) approximation agrees well with configuration interaction results using several Landau levels for a wide range of confining and Coulomb interaction strengths. Within the optimized LLL approximation, we study several phase transitions beyond the maximum density droplet for four to nine electrons and find similar patterns in the phase-space diagrams for angular momenta up to N(N+1)/2. Calculations for larger angular momentum reveal unpolarized phases for filling factors up to nu=1/3.

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