Anharmonic lattice dynamics of solid potassium

An interionic potential proposed by Dagens, Rasolt, and Taylor has been used in classical computer-simulation experiments on solid K at 162.5 and 311 K. Results for the dynamical structure factor S(→Q,ω) are compared with lattice-dynamical calculations employing the self-consistent harmonic approximation plus cubic anharmonic corrections. The lattice-dynamical calculations are in good accord with the simulation data at the lower temperature but near the melting point the simulation data yield considerably broader phonons, in qualitative agreement with experimental neutron-scattering data. The anharmonic interference effect which couples the one-phonon S₁(→Q,ω) to the multiphonon background is also discussed.