Spectroscopy of sodium atom in liquid helium cluster: a symmetry adapted cluster-configuration interaction (SAC-CI) study

Excitation line shift of the principal resonance line of sodium atom embedded in liquid helium is estimated using symmetry adapted cluster-configuration interaction (SAC-CI) method with a reasonably good choice of basis set. The effect of the liquid surroundings is considered by taking only the nearest neighbor interaction using several model clusters of helium atoms with a centrally located isolated sodium atom. The transition wavelength of the ²P ← ²S line of Na is estimated both for the free Na and for the Na atom centrally located inside a model helium cluster. The shift depends obviously on the model cluster and the distance of the central Na atom from the surrounding He atom. With a physically realizable structure, SAC-CI calculation correctly predicts the theoretical results obtained previously on such estimates.