Ab initio structural, electronic and optical properties of orthorhombic CaGeO3CaGeO3

Orthorhombic CaGeO3CaGeO3 is studied using density-functional theory (DFT) considering both the local density and generalized gradient approximations, LDA and GGA, respectively. The electronic band structure, density of states, dielectric function and optical absorption are calculated. Two very close indirect (S→ΓS→Γ) and direct (Γ→ΓΓ→Γ) band gap energies of 1.68 eV (2.31 eV) and 1.75 eV (2.41 eV) were obtained within the GGA (LDA) approximation, as well as the effective masses for electrons and holes. Comparing with orthorhombic CaCO3 (aragonite), the substitution of carbon by germanium changes the localization of the valence band maximum of the indirect transition, and decreases by almost 2.0 eV the Kohn–Sham band gap energies.

Orthorhombic CaGeO3CaGeO3 was studied using density-functional theory (DFT) considering both the local density and generalized gradient approximations, LDA and GGA, respectively. The electronic band structure, density of states, effective masses, dielectric function and optical absorption were obtained after geometry optimization of the unit cell.Figure optionsDownload as PowerPoint slide