Open AccessCalculation of thermodynamic, electronic, and optical properties of monoclinic Mg2NiH4
Author(s) -
Whittier Myers,
L-W. Wang,
Thomas J. Richardson,
M. Rubín
Publication year - 2002
Publication title -
journal of applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.699
H-Index - 319
eISSN - 1089-7550
pISSN - 0021-8979
DOI - 10.1063/1.1454206
Subject(s) - monoclinic crystal system , band gap , ab initio , semiconductor , dielectric , materials science , phase (matter) , ab initio quantum chemistry methods , tetrahedron , diffraction , density functional theory , chemistry , thermodynamics , crystallography , computational chemistry , optics , crystal structure , molecule , physics , optoelectronics , organic chemistry
Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.
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