Abstract
Starting from the X-ray diffraction data of Huang et al. we have optimized the atomic positions by minimization of the forces (1 mRy/au) using Perdew-Burke-Ernzerhof generalized gradient approximation (GGA). From the relaxed geometry the electronic structure and the chemical bonding are determined. We have employed the full potential linear augmented plane wave (FPLAPW) method as embodied in the WIEN2k code. In order to get a better estimate of the energy gap we have used the modified Becke-Johnson potential (mBJ) exchange-correlation potential. Our calculations show that the conduction band minimum (CBM) is situated at the centre of the Brillouin zone (BZ) and the valence band maximum (VBM) is located between W and T symmetry points of the BZ, indicating that bismuth subcarbonate is a semiconductor with an indirect band gap of about 0.8 eV. The electrons effective mass ratio (m(e)(*)/me) around G point are calculated. The partial density of states and the electronic charge density distribution shows that there exists a strong covalent bond between C and O atoms. Our calculated bond lengths and angles show very good agreement with the experimental data. (C) 2014 Elsevier Masson SAS. All rights reserved.