Roton and vibron density of states in solid parahydrogen

Abstract

We present the results for the density of states of J = 2 rotons and ν = 1 vibrons in solid (hcp) parahydrogen as well as the joint roton–vibron density of states for noninteracting rotons and vibrons. The width and the shape of the joint roton–vibron density of states agree with those of the Raman and IR spectra in the 4490–4520 cm−1 spectral region lending support to the idea that the latter are due to the Q1(0) + S0(0) double transitions in the fundamental band of solid parahydrogen. However, there are differences between the features of the experimental (Raman and IR) spectra and the joint density of states that indicate that the matrix element effects and perhaps also the effects of interaction between the rotons and the vibrons are important in determining the exact features in these spectra.