PaperPhonon spectral functions and ground-state energy of quantum crystals in perturbation theory with a variationally optimum correlated basis setT.R. Koehler, N.R. WerthamerPhysical Review A
PaperSelf-consistent phonon calculation of the β phase and the α-β transition in solid nitrogenJ.C. Raich, N.S. Gillis, et al.The Journal of Chemical Physics