We have proposed the use of High-Multiplicity Natural Orbitals (HMNOs) as a substitute for molecular orbitals in excited state Multi-Reference Configuration Interaction (MRCI). HMNOs are natural orbitals that are generated by a triplet (or higher multiplicity) ground state correlated calculation, allowing us to produce orbitals that are cheap, yet suitable for use in excited state calculations. In our previous work1, we found that the MRCI/HMNO approach reliably reproduced vertical excitation energies obtained from standard MRCI for several representative molecules. As we are ultimately interested in probing excited state potential energy surfaces, we must decide if the MRCI/HMNO method is suitable for describing smooth potential energy surfaces, specifically in the regions where there are conical intersections. We find that the MRCI/HMNO method shows great promise in application to both conical intersections and potential energy surfaces. We also hope to extend the method to include gradient calculations in the future.1Lu Z.; Matsika S. J. Chem. Theory Comput. 2012, 8, 509-517

Get <i>excited </i>with High-Multiplicity Natural Orbitals

244th National Meeting (2012)

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Get excited with High-Multiplicity Natural Orbitals