Electronic structure and lattice vibrations of Ca2CuO2Cl2:: A hybrid density functional study

The electronic structure and phonon modes of Ca2CuO2Cl2 have been calculated using hybrid density functional theory (HDFT) methods. The material is correctly predicted to be an antiferromagnetic insulator with a band gap of around 2 eV. Lattice parameters and atomic positions are in good agreement with experiment with a maximum error in lattice constant less than 2%. Phonon modes were calculated using HDFT Hamiltonians containing Hartree-Fock (HF) exchange with weights of 0.2, 0.3, or 0.4. Phonon mode frequencies typically shift upward by 4% on increasing the HF exchange weight by 0.1. Computed Cu-O stretching modes of E-u symmetry at 615 and 334 cm(-1) are in good agreement with recently reported IR absorption frequencies at 620 and 350 cm(-1).