ABINITIO CONFIGURATION-INTERACTION STUDY OF EXCITED-STATES OF LINA3 AND LI2NA2 CLUSTERS - INTERPRETATION OF ABSORPTION-SPECTRA

The ab initio configuration-interaction (CI) study of excited states o f mixed alkali metal tetramers LiNa3 and Li2Na2 accounts for spectrosc opic patterns obtained from the depletion spectra of neutral species, reproduces observed excitation energies and intensities for allowed tr ansitions, and permits an assignment of cluster structures. For both m ixed tetramers, the rhombic forms with a Li atom or atoms on the short diagonal are the most stable structures and give rise to predicted sp ectra in full agreement with the measured ones. The exact location of Li atoms seems to be more important in Li2Na2 than in LiNa3 since in t he former case, only one isomer reproduces all features of the recorde d spectrum.