First-Principles Calculations of the Structural, Electronic, and Optical Properties of Cesium Bromide

Abstract

First-principles calculations within density functional theory using the generalized gradient approximation (GGA) in the siesta code were performed to investigate the structural, electronic, and optical properties of cesium bromide. The calculated structural parameters show good agreement with previous studies, giving a lattice constant of 4.2506 The band structure shows an indirect fundamental gap of 4.60 eV ( ) and the direct gap of 4.66 eV at Γ. These values are close to previous GGA results but well below the experimental gap, consistent with the known underestimation of band gaps by GGA. Partial density of states analysis indicates the valence band is dominated by Br-4p states and the lowest conduction bands by Cs-5d states. Interband absorption begins near 4.48eV, slightly below the direct gap, and the main absorption peak of the imaginary dielectric function occurs at 6.82 eV, the static refractive index is (1.53). These results provide GGA- level set of structural, electronic, and optical parameters for cesium bromide in the pm-3m structure.