Max-Planck-Inst. Festkoerperforsch., Stuttgart , D-7000/80, Fed. Rep. Ger.

Relativistic linear muffin-tin orbital (LMTO) calcns. of the enthalpy for potassium as a function of pressure and crystal structure (bcc, fcc, ideal hcp, and ideal Sm-type lattices) indicate a structural bcc-fcc phase transition at 107 kbar. This agrees with the obsd. room-temp. transition at 114 kbar, and is explained as being due to an s- to d-electron transfer. The pressure-induced changes of the Fermi surface and av. optical mass were also investigated. The results of the band-structure calcns. were used to derive the optical cond. of potassium at the equil. lattice const. and under pressure. Good agreement was obtained with exptl. optical data at zero pressure. Under compression the interband transitions become more intensified, as is obsd. exptl. New features in the optical spectra of the fcc phase are predicted and their origin in the k space is examd.
 

Physical Review B, 39 8096-106, 1989.