LDA simulations of pressure-induced anomalies in c/a and electric-field gradients for Zn and Cd

We present results of ab initio simulations of the effect of hydrostatic pressure on the electronic structure, lattice parameters, and electric-field gradients (EFG) for hcp Zn and Cd using the full-potential linear muffin-tin orbital method in conjunction with the new Perdew-Burke-Ernzerhof generalized gradient approximation (GGA) to the density functional for exchange correlation. Theoretical equilibrium volumes for Zn and Cd cue found to be in excellent agreement with experiment (whereas non-GGA corrected local density approximation underestimates them by as much as 10%). We find an anomaly in the pressure dependence of c/a at reduced unit cell volumes (at V/V-0 similar or equal to 0.89 for Zn and in a broad region from V/V-0=0.92 to 0.85 for Cd) and a similar anomaly in the EFG tenser. At the same time we do not find the electronic topological transition due to the destruction of a giant Kohn anomaly which was previously thought to be responsible for the lattice anomalies in Zn.