Knowledge Bank

The OVC version [1] of the multiconfiguration self consistent field approach in ab initio quantum-mechanical computations of small molecules has met with a reasonable measure of success. Even when pushed to the hilt (as we have attempted to do for low-lying states of $Li2$, for example [1]), the OVC scheme gave potential curves which were slightly misshapen ($\omega e$ and $Be$ too small, for example). Effective core potential computations [2] and very refined spectroscopic observations [3,4] help to understand and quantify those small defects.