Abstract
A pressure-induced simultaneous metal-insulator transition (MIT) and structural-phase transformation (from the B1 to B2 phase) in lithium hydride with about 1.3% volume collapse has been predicted by means of the generalized-gradient approximation (GGA) in conjunction with an all-electron GW approximation method. The local-density approximation (LDA) wrongly predicts that the MIT occurs before the structural phase transition, whereas the GGA predicts the correct transition but with a very small band gap of the B1 phase at the transition. It is also shown that only the use of the GGA together with the zero-point vibration produces an equilibrium lattice parameter, bulk modulus, and an equation of state that are in excellent agreement with experiment.