Rotational motion under pressure in the solid molecular hydrogen isotopes

Rotational states as functions of pressure for H₂, D₂, T₂ HD, and HT molecules are calculated in the corresponding molecular solids. Sudden transitions from spherically symmetric rotational states occur in para-H₂, para-T₂, ortho-D₂, and in HD and HT as the pressure increases. Only the predicted T₂ transition pressure of about 24 kbar lies within current experimentally accessible ranges. All other transitions occur in the region 150–300 kbar.Supported in part by NSF Grant No. GH-35581, National Aeronautics and Space Administration Grant No. NGR 06-002-159, and United States Energy Research and Development Administration.