Computer simulation of site formation for Na atoms trapped in Ar and Xe solids

Existing data on Na-rare gas and rare gas–rare gas dimer potentials have been used in a computer program to simulate the formation of trapping sites for Na atoms isolated in Ar and Xe solids. The dimer potentials have also been employed to calculate the matrix perturbed energy-level structure of the Na atoms to obtain theoretical wavelengths for absorption and emission bands corresponding to the sites formed in the simulations. The results support the view that the stable blue-shifted absorption band of Na in Ar and Xe is due to a substitutional site and that the thermally unstable unshifted band results from amorphous sites evolving from two-atom vacancies. In all cases, the simulated sites exhibited a local symmetry sufficient to produce a degeneracy in the perturbed Na 3p state levels.