Ab Initio Structure and Dynamics of Beryllium Monofluoride\nand Its Anion

The accurate potential\nenergy functions of beryllium monofluoride,\nBeF, and its anion, BeF<sup>–</sup>, have been determined from\nab initio calculations using the coupled-cluster approach, up to the\nCCSDTQP level of approximation, in conjunction with the augmented\ncorrelation-consistent core–valence basis sets, aug-cc-pCV<i>n</i>Z, up to septuple-zeta quality. The vibration–rotation\nenergy levels of the two species were predicted to near the “spectroscopic”\naccuracy. Changes in the electron density distribution upon formation\nof the Be–F chemical bond are discussed.