Self-trapped exciton and rare-gas impurity centers in solid Ne

The structure of the atomic-type self-trapped exciton in solid Ne is studied using a hybrid method in which the inner shells of an atom are represented by the ion-size parameters of Bartram, Stoneham, and Gash, while the two outermost $s$,$p$ shells are treated exactly as in the extended-ion model. The electronic wave function and the lattice relaxation are determined self-consistently by minimization of the total energy of the system. The lattice is found to dilate around the excited Ne atom by an amount corresponding to about five vacancies. The calculated absorption energy of the self-trapped exciton for ${\Gamma }_1\to {\Gamma }_{15}$ (atomic $3s\to 3p$) transition is in good agreement with the experimental data of Suemoto and Kanzaki. The impurity centers of rare-gas atoms in a Ne host are also studied by the same method. The results show the existence of a small cavity around the impurity atoms, and account satisfactorily for the changes in the optical transition energies from gas to solid.