Ab initio characterization of the aluminum dimer in its X and A electronic states.

Abstract

The potential energy functions of the aluminum dimer, Al2 , in its lowest-energy electronic states, X and A have been determined from ab initio calculations using the multi-reference averaged coupled-pair functional method in conjunction with the correlation-consistent basis sets up to septuple-zeta quality. The core-electron correlation, scalar relativistic, and spin-orbit effects were taken into account. The vibration-rotation energy levels for both the states of Al2 were calculated to near the "spectroscopic" accuracy. The state was unequivocally confirmed to be the electronic ground state of Al2 , and the electronic term value of the state was predicted to be 247 cm-1 . The energies and intensities of direct electronic-vibration transitions X ↔A were predicted.