An Anharmonic Theory of the Rotational Excitation in Solid Orthodeuterium under High Pressure

Abstract

A theoretical study is presented of the spherically symmetric phase (SP) of solid orthodeuterium at high pressure, where the processes making one roton split into two and three ones are taken into account. The Raman spectra due to rotational excitations are calculated, where the width of three peaks in the spectra becomes broad with increasing pressure in good agreement with the experiment by Silvera and Wijngaarden. The transition from the SP to the phase of broken symmetry is studied by taking account of the correlation energy. A rapid shift of the frequency of vibron (intramolecular-vibrational excitation) is predicted to occur in the close vicinity of transition pressure.