MODELING OF HALF-HEUSLER CRYSTALS WITH THE CHALCOPYRITE STRUCTURE: LI2MGZNX2 (X = N, P, AS, SB)
Yu. M. Basalaev, M. V. Starodubtseva
Kemerovo State University, Novosibirsk, Russia
Keywords: халькопирит, полухейслеровское соединение, зонная структура, электронная плотность, деформационная плотность, химическая связь, chalcopyrite, half-Heusler compound, band structure, electron density, deformation density, chemical bond
Abstract
A model of Li2MgZn X 2 half-Heusler compounds with the chalcopyrite structure is considered. The electronic structure is studied from first principles, showing that Li2MgZn X 2 are direct-gap crystals, except for pseudo-direct-gap Li2MgZnP2, with a band gap of 2.7 eV, 2.2 eV, 3.3 eV, and 2.5 eV for X = N, P, As, and Sb, respectively. The band structure and chemical bonding in the model crystals are found to be similar to those in LiMg X and LiZn X half-Heusler crystals. Total electron density and deformation electron density distributions are obtained. It is found that Mg- X and Zn- X ionic-covalent bonds are stronger than Li- X ionic bonds in Li2MgZn X 2 crystals, which allows Li atoms to move in the space between Mg X 4 and Zn X 4 cation tetrahedra.
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