Abstract
The periodic unrestricted Hartree-Fock method has been used to calculate the ground-state spin-polarized wave function and total energy of tetragonal . Contracted Gaussian-type functions represent the atomic orbitals of Fe and F atoms. The nature of the antiferromagnetic insulator, with a d-d type band gap, is reproduced correctly by the calculations. On the basis of the density of electron states, Mulliken population data, and charge- and spin-density maps, the / splitting of states is proved for the ion, consistent with the Jahn-Teller distortion of the octahedron. A limited charge back transfer from to is observed, with =+1.84‖e‖. The equilibrium structural configuration and its evolution with pressure up to 12 GPa have been calculated, including internal relaxation. The athermal equation of state, structural, and elastic parameters show a good agreement with experimental data.
- Received 17 March 1995
DOI:https://doi.org/10.1103/PhysRevB.52.2422
©1995 American Physical Society