Theory of the interaction of the lattice vibrations with the vibrational excitations in solid hydrogen

The theory of the interaction of the vibrational excitations (vibrons) with the lattice vibrations in solid hydrogen is developed. The phonons are treated in the self-consistent harmonic (SCH) approximation appropriate to quantum crystals. The vibron–phonon interaction is expanded in terms of the SCH phonon operators rather than in powers of the displacements of the molecules from their equilibrium positions. First- and second-order perturbation corrections to the vibron energies arising from the vibron–phonon coupling are calculated. The effect of the anharmonicity of the intramolecular vibrations in conjunction with the vibron–phonon coupling is also discussed.