Max-Planck-Inst. Festkoerperforsch., Stuttgart , D-7000/80, Germany

D.-functional linear response approach is developed in the framework of conventional band theory anal. It is based on the variational solns. of 1-electron Schroedinger equations in linear order. Due to incompletness of the basis sets in band structure calcns. large contributions to the std. perturbation theory exist. These terms disappear only in plane wave pseudopotential calcns. The formulation allows to avoid the problem of summation over higher excited states in all cases. The approach is applied to calc. phonon dispersions in Nb and the results are in excellent agreement with expt.
 

International Journal of Modern Physics. B, 7 197-202, 1993.