Prediction study of structural, electronic and optical properties of 4C₁₆H₁₀Br₂O₂ Bis (m-bromobenzoyl) methane crystals

By first-principles calculations with density functional theory and a pseudopotential approach, the structural, electronic, and optical properties of the anhydrous 4C(16)H(10)Br(2)O(2) Bis (2-Bromobenzoyl) Methane crystals in Pbnc (N degrees 60) and P2(1)/c (N degrees 14) space group are investigated. All computations are determined by a generalized gradient approximation, local density approximation and an ultra-soft pseudopotential. The calculated equilibrium parameters are in good agreement with their available experimental data. This calculation shows that the GGA/PW91 functional overestimate the lattice constant, unlike the LDA/CA-PZ. The Br-C bond distance of 1.856 (1.902) & Aring; is comparable with experimental value of 1.901 (1.896) & Aring; in Pbnc (P2(1)/c) space groups. The direct band gap nature is obtained for both space groups Pbnc and P2(1)/c, since the maximum of the valence band and the minimum of the conduction band are both situated at the YA center.