A note on the Renner splitting of the first ionized state of BeF2

Abstract MCSCF calculations were carried out for the potential energy curves along the bending motion for the lowest 2 A 2 and the two lowest 2 B 2 states of BeF 2 + with an extended basis set and a large complete active space. Our results indicate that the Renner splitting of the 2 Π g state of BeF 2 + presents a pattern with a bent geometry only for the lowest state. This pattern represents one of the three types of Renner splittings suggested by Pople and Longuet-Higgins, but is in contrast to findings from later theoretical studies. We show that the disagreement is caused by the poor quality of the atomic basis set employed in the previous work by comparing results of calculations at the UHF and OSRHF level for gradually improving atomic basis sets.