Improved description of the orbital relaxation effect by practical use of the self-energy
Article first published online: 4 FEB 2014
Copyright © 2014 Wiley Periodicals, Inc.
International Journal of Quantum Chemistry
Volume 114, Issue 9, pages 577–586, 5 May 2014
How to Cite
How to cite this article: Int. J. Quantum Chem. 2014, 114, 577–586. DOI: 10.1002/qua.24625, , .
- Issue published online: 19 MAR 2014
- Article first published online: 4 FEB 2014
- Manuscript Revised: 4 DEC 2013
- Manuscript Accepted: 4 DEC 2013
- Manuscript Received: 19 AUG 2013
- Rikkyo University
- electronic structure theory;
- electronic excitation;
- polarization propagator;
- electron propagator
The self-energy shift in the orbital relaxation (OR) term of the polarization propagator complete through the second-order is presented. In combination with the optimal damping parameter in the OR term, the modified propagator produces the excitation energy of the coupled-cluster with singles and doubles (CCSD) accuracy. The self-energy shift requires the floating-point operation of , where N refers to the magnitude of the molecular size. Because the second-order polarization propagator requires the floating-point operation of , the additional computational effort to construct the self-energy is negligibly small. Numerical results are shown for several molecules including glycine, 2,3,5,6-tetrafluorobenzene, and naphthalene, and promising agreements with those of CCSD are confirmed within less than 0.2 eV. The basis set dependence is also tested for the water molecule using aug-cc-pV NZ (N = D–7), where this newly developed approach mimics the behavior of the CCSD values. The self-energy shifting for the second-order response matrix in combination with the use of a dumping parameter is efficiently implemented for calculations of medium-sized molecular systems, including glycine and naphthalene. The developed approach provides CCSD-like accuracy at a more affordable computational expense. © 2014 Wiley Periodicals, Inc.