Hole trapping in Li_xNi_1-xO

Calculations are reported for a hole associated with a lithium impurity in NiO. The method is based on Hartree-Fock molecular clusters embedded in a classical shell-model lattice, with consistent treatment of distortion and polarization. It is shown that the hole is trapped in oxygen 2p states rather than in nickel 3d states, in agreement with experimental X-ray absorption spectroscopy results. In the static lattice approximation the hole localizes on a single oxygen nearest neighbour of the lithium ion, rather than in an O_h-symmetric distribution among all such neighbours.