Calculation of the pressure dependence of the EFG in BCT In, HCP Ti and Zn from energy band structures

The energy band structures of bct In, hcp Ti and Zn have been calculated at various lattice parameters using the full potential linearized augmented plane wave method. It has been shown for several hcp metals that the EFG at the atomic sites can be obtained from the total self-consistent charge densities without further approximations. The calculated EFGs for the systems studied here are in good agreement with experiment and originate mainly from the anisotropy of the valence states, while contributions from the core states and the lattice are small. From calculations for different c/a ratios and volumes we can deduce the derivatives d(ln EFG)/dp, but also d(ln EFG)/d(ln V) and d(ln EFG)/d(ln c/a), quantities, which are not easily accessible by experiment. (orig.)