First-principles study of electronic, dynamical and thermodynamic properties of γ-Li₄SiO₄

Abstract

We have studied the structural, electronic and dynamic properties of γ-Li 4 SiO 4 (lithium orthosilicate) using density functional theory (DFT) with the generalized gradient approximation (GGA). The crystal structure is fully relaxed. The electronic band structure and Density of States (DOS) calculations indicate that γ-Li 4 SiO 4 is an insulator with an indirect band gap of 5.19 eV and it has a conduction band with the width of 5.92 eV and two valance bands with the width of 4.45 eV and 0.57 eV, respectively. In the partial DOS, Li and Si electronic densities increase more sharply than O atoms. Comparing with previous works, the phonon dispersion curves without negative frequencies are calculated along high symmetry points. By adding the Born effective charges in the phonon calculation, the LO-TO splittings are also calculated which indicate that γ-Li 4 SiO 4 is polar and anisotropic. The optical modes of phonon frequencies at Γ point are assigned as Raman and Infrared-active modes. Additionally, the thermodynamic functions (entropy, internal energy, Helmholtz free energies and constant-volume specific heats) were determined by using the phonon DOS. The calculated results may provide useful guidance of γ-Li 4 SiO 4 for future experimental studies in some degree. , 65.40.-b, 71.20.-b 1550128-1 Int. J. Mod. Phys. B 2015.29. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 08/19/15. For personal use only.

Revealing the different performance of Li4SiO4 and Ca2SiO4 for CO2 adsorption by density functional theory

“…The bulk structure of Li 4 SiO 4 with the monoclinic phase, which space group is P21/m (no. 11), [33][34][35] was optimized. The unit cell of Li 4 SiO 4 contains 126 atoms, including 14 [SiO 4 ] 4À tetrahedra and 56 Li atoms, as shown in Fig.…”