Ab initio Hartree–Fock study of lithium and sodium sulfides: electronic and scattering properties

Abstract

The electronic structure of lithium sulfide and sodium sulfide in the solid state is established at the Hartree-Fock level, as implemented in the CRYSTAL program. Two all-electron basis sets are adopted for each compound. Mulliken analysis, band structure, density of states and electron charge density are studied: these exhibit the highly ionic character of both compounds; this seems rather surprising because of the weak electronegativity and large polarizability of the sulfur. Form factors of the sulfur are deduced from the structure factors and analysed in order to show the deformations of this anion in the crystal environment. Finally, electron momentum density and Compton profiles confirm the almost fully ionic character of the compounds and prove the quality of the calculated wavefunctions.

Ab initio calculation of dynamic polarizability and dielectric constant of carbon and silicon cubic crystals

“…3 Recently, Compton profiles, for which electronic correlation effects cannot be neglected, 4 have been also calculated using wave functions built from Ž . the density functional theory DFT in the local Ž .…”

First‐principles study of electronic structure and ground‐state properties of alkali‐metal sulfides – Li2S, Na2S, K2S and Rb2S

“…The electronic band structure of these materials at ambient conditions was discussed by Zhuravlev et al [6] using the self-consistent pseudopotential method. The linear combinations of atomic orbitals by Hartree-Fock (LCAO-HF) studies [7] are undertaken to determine the valence-band width and the density of states for Li 2 S and Na 2 S.…”

FP-LAPW investigation of mechanical and thermodynamic properties of Na2X (X = S and Se) under pressure and temperature effects

“…At low temperatures, the shapes of the curves of C V and C P are similar. As known, the increase of heat capacity with T 3 at low temperatures is due to the harmonic approximation of the [29], c [26], d [20], e [62], f [63], g [64], h [65], i [66], k [67], l [23], m [68], n [69], o [31], p [70]. Debye model.…”

“…In the Na 2 X (X = S, Se) compounds, the metal atoms (Na) are located at (0.25, 0.25, 0.25) and (0.75, 0.75, 0.75) and the atoms (X) are located at (0, 0, 0). These compounds are subjects of many experimental and theoretical works, focusing on structural phase transformation [17][18][19][20][21][22] and electronic properties [23][24][25][26][27]. The electronic band structure of these materials at ambient conditions was discussed [25] using the selfconsistent pseudo-potential method.…”