Ab-initio determination of X-ray structure factors and the Compton profiles of CdO

X-ray structure factors and Compton profiles of CdO are presented in this work. The theoretical calculations are performed employing the first-principles linear combination of atomic orbitals (LCAO) method using the CRYSTAL code. The computations are made considering the Perdew–Burke–Ernzerhof (PBE) correlation energy functional and Becke's ansatz for the exchange. The computed X-ray structure factors for B1 structure are compared with the available experimental data. To compare the averaged theoretical Compton profile, first ever measurement on polycrystalline CdO is reported using 5Ci 241Am Compton spectrometer. The ionic model calculations have been used to estimate charge transfer in CdO. The agreement is, however, better with the LCAO calculation. The first-principles calculations of equilibrium lattice constants, bulk moduli and its pressure derivative of competing B1 and B2 phases of CdO are also reported and compared with the available results. The computed transition pressure for B1 → B2 structural phase transition is in good agreement with the experimental findings. Moreover, the electronic band structures show that B1 phase has indirect band gap of 0.43 eV in reasonable agreement with the experiments and B2 phase exhibits negative band gap of 0.9 eV.