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A theoretical study on the spatial configurations of the catalytic dehydrogenation of the pre- and post- Ti-doped NaAlH4(001)2×2×1 supercell surface crystals was performed by using the Car-Parrinello molecular dynamics (CPMD) method at 333 K (60 ℃). It was be found that two of the Al—H bond lengths increased from approximately 1.64 to 1.74 and 1.93 respectively in the AlH4 groups of the Ti-doped alloy. Compared with this change, the four Al—H bond lengths almost kept invariant in the AlH4 group of un-doped alloy, which means that it was easier to dehydrogenate for the Ti-doped alloy than un-doped alloy. There was no bonding tendency between atom Ti and Al observed, which is probably because the temperature in the simulation process is not high enough. Based on the obtained surface crystal configuration, the Ti K-edge x ray absorption near-edge structure (XANES) spectra of the TiAl3, TiH2 crystals and Na8Ti8Al16H64(001) surface crystal have been calculated by using the full-potential linearized augmented plane wave method (FPLAPW). It was also found that the atom Ti may not only exist in the mixture of TiAl3 and TiH2 but also probably partially substitute for the Na atoms in NaAlH4 surface crystal, by comparing the experimental XANES and edge x ray absorption fine structure (EXAFS) spectra.
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Keywords:
- NaAlH4 /
- Car-Parrinello ab initio molecular dynamics /
- density functional theory /
- x ray absorption near-edge structure
[1] Wirth T E, Gray C B, Podesta J D 2003 Foreign Aff. 82 132
[2] Kerr R A, Service R F 2005 Science 309 101
[3] iguez J, Yildirim T, Udovic T J, Sulic M, Jensen C M 2004 Phys. Rev. B 70 060101
[4] iguez J, Yildirim T 2005 Appl. Phys. Lett. 86 103109
[5] iguez J, Yildirim T 2007 J. Phys. :Condens. Matter 19 176007
[6] Herberg J L, Maxwell R S, Majzoub E H 2006 J. Alloys Compd. 417 39
[7] Majzoub E H, Herberg J L, Stumpf R, Spangler S, Maxwell R S 2005 J. Alloys Compd. 394 265
[8] Graetz J, Reilly J J, Johnson J, Ignatov A Y, Tyson T A 2004 Appl. Phys. Lett. 85 500
[9] Baldé C P, Stil H A, van der Eerden A M J, de Jong K P, Bitter J H 2007 J. Phys. Chem. C 111 2797
[10] Ignatov A Y, Graetz J, Chaudhuri S, Salguero T T, Vajo J J, Meyer M S, Pinkerton F E, Tyson T A 2007 AIP Conference Proceedings 882 613
[11] Tang Y H, Lin L W, Guo C 2006 Aata Phys. Sin. 55 4197 (in Chinese) [唐元洪、林良武、郭 池 2006 55 4197]
[12] Cao H B, Chen D L, He L H, Zhang J R, Wang F W, Wu Z Y, Yan Q W 2007 Chin. Phys. 16 784
[13] Ma C Y, Cui M Q, Zhang L Y, Wu X, Zhou K J, Wu Z Y, Chen X,Zhao Y D, Zheng L 2008 Aata Phys. Sin. 57 3868 (in Chinese) [马陈燕、崔明启、张凌云、巫 翔、周克瑾、吴自玉、陈 兴、赵屹东、郑 雷 2008 57 3868]
[14] Car R, Parrinello M 1985 Phys. Rev. Lett. 55 2471
[15] Payne M C, Teter M P, Allan D C, Arias T A, Joannopoulos J D 1992 Rev. Mod. Phys. 64 1045
[16] Vanderbilt D 1990 Phys. Rev. B 41 7892
[17] Laasonen K, Pasquarello A, Car R, Lee C, Vanderbilt D 1993 Phys. Rev. B 47 10142
[18] Perdew J P, Burke K, Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[19] Verlet L 1967 Phys. Rev. 159 98
[20] Nosé S 1984 Molec. Phys. 52 255
[21] Hoover W G 1985 Phys. Rev. A 31 1695
[22] Blaha P, Schwarz K, Sorantin P, Trickey S B 1990 Compupt. Phys. Commun. 59 399
[23] Schwarz K, Blaha P, Madsen G K H 2002 Compupt. Phys. Commun. 147 71
[24] Wu Z, Cohen R E 2006 Phys. Rev. B 73 235116
[25] Chaudhuri S, Muckerman J T 2005 Phys. Chem. B 109 6952
[26] Colinet C, Pasturel A 2002 J. Phys. : Condens. Matter 14 6713
[27] Liu J, Ge Q 2006 Chem. Commun. 17 1822
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[1] Wirth T E, Gray C B, Podesta J D 2003 Foreign Aff. 82 132
[2] Kerr R A, Service R F 2005 Science 309 101
[3] iguez J, Yildirim T, Udovic T J, Sulic M, Jensen C M 2004 Phys. Rev. B 70 060101
[4] iguez J, Yildirim T 2005 Appl. Phys. Lett. 86 103109
[5] iguez J, Yildirim T 2007 J. Phys. :Condens. Matter 19 176007
[6] Herberg J L, Maxwell R S, Majzoub E H 2006 J. Alloys Compd. 417 39
[7] Majzoub E H, Herberg J L, Stumpf R, Spangler S, Maxwell R S 2005 J. Alloys Compd. 394 265
[8] Graetz J, Reilly J J, Johnson J, Ignatov A Y, Tyson T A 2004 Appl. Phys. Lett. 85 500
[9] Baldé C P, Stil H A, van der Eerden A M J, de Jong K P, Bitter J H 2007 J. Phys. Chem. C 111 2797
[10] Ignatov A Y, Graetz J, Chaudhuri S, Salguero T T, Vajo J J, Meyer M S, Pinkerton F E, Tyson T A 2007 AIP Conference Proceedings 882 613
[11] Tang Y H, Lin L W, Guo C 2006 Aata Phys. Sin. 55 4197 (in Chinese) [唐元洪、林良武、郭 池 2006 55 4197]
[12] Cao H B, Chen D L, He L H, Zhang J R, Wang F W, Wu Z Y, Yan Q W 2007 Chin. Phys. 16 784
[13] Ma C Y, Cui M Q, Zhang L Y, Wu X, Zhou K J, Wu Z Y, Chen X,Zhao Y D, Zheng L 2008 Aata Phys. Sin. 57 3868 (in Chinese) [马陈燕、崔明启、张凌云、巫 翔、周克瑾、吴自玉、陈 兴、赵屹东、郑 雷 2008 57 3868]
[14] Car R, Parrinello M 1985 Phys. Rev. Lett. 55 2471
[15] Payne M C, Teter M P, Allan D C, Arias T A, Joannopoulos J D 1992 Rev. Mod. Phys. 64 1045
[16] Vanderbilt D 1990 Phys. Rev. B 41 7892
[17] Laasonen K, Pasquarello A, Car R, Lee C, Vanderbilt D 1993 Phys. Rev. B 47 10142
[18] Perdew J P, Burke K, Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[19] Verlet L 1967 Phys. Rev. 159 98
[20] Nosé S 1984 Molec. Phys. 52 255
[21] Hoover W G 1985 Phys. Rev. A 31 1695
[22] Blaha P, Schwarz K, Sorantin P, Trickey S B 1990 Compupt. Phys. Commun. 59 399
[23] Schwarz K, Blaha P, Madsen G K H 2002 Compupt. Phys. Commun. 147 71
[24] Wu Z, Cohen R E 2006 Phys. Rev. B 73 235116
[25] Chaudhuri S, Muckerman J T 2005 Phys. Chem. B 109 6952
[26] Colinet C, Pasturel A 2002 J. Phys. : Condens. Matter 14 6713
[27] Liu J, Ge Q 2006 Chem. Commun. 17 1822
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