The modern VB descriptions of CH2, CH2+, SiH2, and SiH2+
Abstract
Spin-coupled theory, which represents the modern form of valence bond theory, is used to investigate the (correlated) electronic structure of CH2, SiH2, CH2+, and SiH2+ in various states. The pictures that emerge for the bonding in these systems are remarkably similar to the classical ideas of covalent bonds constructed from spx-like hybrids and H(1s) orbitals, but there are also some important differences.