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-pCVZ, 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.