Ab Initio Structure and Dynamics of Beryllium Monofluoride and Its Anion

The accurate potential energy functions of beryllium monofluoride, BeF, and its anion, BeF-, have been determined from ab initio calculations using the coupled-cluster approach, up to the CCSDTQP level of approximation, in conjunction with the augmented correlation-consistent core-valence basis sets, aug-cc-pCVnZ, up to septuple-zeta quality. The vibration-rotation energy levels of the two species were predicted to near the "spectroscopic" accuracy. Changes in the electron density distribution upon formation of the Be-F chemical bond are discussed.