Electron wave packet modeling of chemical bonding: Floating and breathing minimal packets with perfect-pairing valence-bond spin coupling

A simple wave packet (WP) modeling of electrons in chemical bonding is examined. It is found that floating and breathing minimal Gaussian WPs with fully non-orthogonal perfect-pairing valence-bond spin coupling yield the ground state potential energy surfaces of LiH, BeH2, CH2, and H2O molecules of comparable quality to a high-level ab initio electron-correlated calculations. A simple form of core pseudo-potential with two parameters is shown to give proper modeling of core–valence interactions.