Pressure dependence of the optical phonon in solid hydrogen and deuterium up to 230 kbar

We have studied the $E_{2g}$ transverse-optical phonon by means of Raman scattering in solid molecular hydrogen and deuterium at pressures up to 230 kbar at 5 K in a diamond anvil cell. With the use of a self-consistent phonon calculation which incorporates anharmonic corrections to the self-energy, phonon frequencies were calculated using an isotropic inter-molecular pair potential. Deviations between theory and experiment point to deficiencies in the potential. The present experimental data can be used as a test on the isotropic part of the intermolecular potential of the solid.