Structural, electronic, and magnetic properties of MnO

We calculate the structural, electronic, and magnetic properties of MnO from first principles, using the full-potential linearized augmented plane-wave method, with both local-density and generalized-gradient approximations to exchange and correlation. We find the ground state to be of rhombohedrally distorted $B1$ structure with compression along the $[111]$ direction, antiferromagnetic with type-II ordering, and insulating, consistent with experiment. We show that the distortion can be understood in terms of a Heisenberg model with distance dependent nearest-neighbor and next-nearest-neighbor interactions determined from first principles. Finally, we show that magnetic ordering can induce significant charge anisotropy, and give predictions for electric-field gradients in the observed rhombohedrally distorted structure.