Theoretical temperature-dependent phonon spectra of solid neon

Recent measurements of the temperature dependence of phonon energies in solid neon do not agree with the results of previous theoretical treatments. This discrepancy is remedied here with a calculation of the one-phonon Green's function by a perturbative method which includes the leading corrections to the lowest order self-consistent phonon theory. The renormalized phonon energy is then identified with the peak of the imaginary part of the Green's function. © 1969 The American Physical Society.