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

MCSCF calculations were carried out for the potential energy curves along the bending motion for the lowest ²A₂ and the two lowest ²B₂ states of BeF₂⁺ with an extended basis set and a large complete active space. Our results indicate that the Renner splitting of the ²Π_g state of BeF₂⁺ 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.