The Restricted Open-Shell Hartree-Fock (ROHF) method is a standard tool used by quantum chemists for studying molecules with unpaired electrons. In this work a problem with some implementations of the ROHF method is presented along with an elegant solution, which has since been added to the GAMESS code. The ground state 2A2 potential energy surface of the 5,5’(4H,4H’)-spirobi[cyclopenta[c]pyrrole] 2,2’6,6’ tetrahydro cation is the molecular test case, which elucidates the underlying problem. The method proposed will also fix Aufbau principle violations reported by Plakhutin in 2009.
Revised: September 14, 2010 |
Published: August 25, 2010
Citation
Glaesemann K.R., and M.W. Schmidt. 2010.On the Ordering of Orbital Energies in High-Spin ROHF.Journal of Physical Chemistry A 114, no. 33:8772-8777.PNNL-SA-71215.doi:10.1021/jp101758y