The influence of generalized gradient corrections to the LDA on predictions of structural phase stability: the Peierls distortion in As and Sb

The crystal structure and phase stability of the group-V elements As and Sb has been investigated by total-energy calculations within the local-density approximation (LDA), without and including generalized gradient corrections (GGC). We show that, contrary to the case of the group-VI elements Se and Te, where the LDA predicts crystal structures with a much smaller difference between the short intra-chain bonds and the long inter-chain bonds than is observed, for As and Sb the LDA leads to equilibrium structures in reasonable, or even good, agreement with experiment and describes the pressure-induced phase transition to a simple cubic structure in Sb (but not in As) very well. The GGC corrections show a tendency to overshoot and do not improve agreement with experiment. In both cases the main effect of the GGC is to add an isotropic pressure to the system, while the local electronic and bonding properties at constant volume remain unchanged.