Removal of orbital degeneracy of the atomic P state for matrix isolated metal atoms

A theoretical study is made of the matrix effects on the absorption spectra of the noble metal atoms Cu, Ag, and Au isolated in Ar, Kr, and Xe matrices. The matrix influence which is discussed in terms of level shifts and additional crystal field splittings is calculated by a nonlocal pseudopotential method. In order to get a threefold splitting of the P level, we assume an axial symmetry for the metal atom site which is caused by a distorted neighborhood in a fcc matrix. This is the first theoretical investigation of the matrix cage distortion around the impurity. The results show that only small variations of the nearest neighbor distances between isolated atoms and matrix atoms are necessary to account for the observed matrix perturbations.