Analysis of chemical bonding in electronic excited states using parity function

The parity function (Schmider, J Chem Phys 1996, 105, 11134) is a projection of the spin‐traced one‐particle density matrix, which is strongly influenced by chemical bonding and its type. In this article, we apply the Parity Function to analyze chemical bonding in the electronic excited states of some small molecules, computed with the time‐dependent density functional theory. The calculations were carried out within the standard linear combination of atomic orbitals framework. We found that the changes in the parity function upon the excitation can be interpreted in terms of chemically relevant concepts such as bond breaking. We hope that the parity function will become a useful tool for understanding electronic excited states. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008