The energetics of the optical excitation of the lowest Rydberg state of a nitric oxide molecule embedded in a neon matrix and the subsequent rearrangement of the solid host are investigated by classical molecular dynamics simulations. Quantum delocalization effects are incorporated through an effective temperature. The relevance of the inclusion of the anharmonicity of crystal site oscillations in the calculation of the effective temperature is evaluated. We show that representing zero point vibrations beyond the harmonic approximation improves the correspondence between the results of molecular dynamics simulations and pump-probe experiments performed on this system. We explored both the steady state spectroscopy and the relaxation dynamics of the doped matrix in this improved representation. The analysis of the Fourier components of particle density reveals that the system simulated within the quantum thermal harmonic correction does not fulfill the translational symmetry of the host crystal.