PHYS 599 |
| The active-space electron-attached (EA) and ionized (IP) equation-of-motion coupled cluster (EOMCC) methods, which use active orbitals to select the dominant higher-than-double, higher than 2p-1h (2-particle-1-hole), and higher than 2h-1p (2-hole-1-particle) excitations, and their symmetry-adapted-cluster configuration interaction (SAC-CI) counterparts provide an ideal framework for performing accurate, low-cost, orthogonally spin-adapted calculations for open-shell species. We will discuss the efficient computer implementation of the active-space EA- and IP-EOMCC methods including up to 3p-2h and 3h-2p excitations, and SAC-CI methods including up to 4p-3h and 4h-3p excitations. Test calculations for excitation energies and potential energy surfaces of several radicals reveal that the active-space methods with 3p-2h and 3h-2p terms provide accurate results for excited states within the Franck-Condon region, while 4p-3h and 4h-3p terms are needed to accurately break bonds. The active-space approaches reproduce the results of their parent EA- and IP-EOMCC and SAC-CI schemes at a fraction of the computational cost. |
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PHYS Poster Session - Computational Spectroscopy and Reaction Dynamics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Physical Chemistry |