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dc.contributor.authorBozkaya, Uğuren_US
dc.contributor.authorTurney, Justin M.en_US
dc.contributor.authorYamaguchi, Yukioen_US
dc.contributor.authorSchaefer, Henry F., IIIen_US
dc.contributor.authorSherrill, C. Daviden_US
dc.date.accessioned2013-05-29T18:28:37Z
dc.date.available2013-05-29T18:28:37Z
dc.date.issued2011-09
dc.identifier.citationBozkaya, Uğur and Turney, Justin M. and Yamaguchi, Yukio and Schaefer, III, Henry F. and Sherrill, C. David, "Quadratically convergent algorithm for orbital optimization in the optimized coupled-cluster doubles method and in orbital-optimize order Møller-Plesset perturbation,” Journal of Chemical Physics, 135, 10 (September 14 2011)en_US
dc.identifier.issn0021-9606
dc.identifier.urihttp://hdl.handle.net/1853/47108
dc.description© 2011 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.3631129en_US
dc.descriptionDOI: 10.1063/1.3631129en_US
dc.description.abstractUsing a Lagrangian-based approach, we present a more elegant derivation of the equations necessary for the variational optimization of the molecular orbitals (MOs) for the coupled-cluster doubles (CCD) method and second-order Møller-Plesset perturbation theory (MP2). These orbital-optimized theories are referred to as OO-CCD and OO-MP2 (or simply “OD” and “OMP2” for short), respectively. We also present an improved algorithm for orbital optimization in these methods. Explicit equations for response density matrices, the MO gradient, and the MO Hessian are reported both in spin-orbital and closed-shell spin-adapted forms. The Newton-Raphson algorithm is used for the optimization procedure using the MO gradient and Hessian. Further, orbital stability analyses are also carried out at correlated levels. The OD and OMP2 approaches are compared with the standard MP2, CCD, CCSD, and CCSD(T) methods. All these methods are applied to H₂O, three diatomics, and the O₄⁺ molecule. Results demonstrate that the CCSD and OD methods give nearly identical results for H₂O and diatomics; however, in symmetry-breaking problems as exemplified by O₄⁺, the OD method provides better results for vibrational frequencies. The OD method has further advantagesover CCSD: its analytic gradients are easier to compute since there is no need to solve the coupledperturbed equations for the orbital response, the computation of one-electron properties are easier because there is no response contribution to the particle density matrices, the variational optimized orbitals can be readily extended to allow inactive orbitals, it avoids spurious second-order poles in its response function, and its transition dipole moments are gauge invariant. The OMP2 has these same advantages over canonical MP2, making it promising for excited state properties via linear response theory. The quadratically convergent orbital-optimization procedure converges quickly for OMP2, and provides molecular properties that are somewhat different than those of MP2 for most of the test cases considered (although they are similar for H₂O). Bond lengths are somewhat longer, and vibrational frequencies somewhat smaller, for OMP2 compared to MP2. In the difficult case of O₄⁺, results for several vibrational frequencies are significantly improved in going from MP2 to OMP2.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectBond lengthsen_US
dc.subjectCoupled cluster calculationsen_US
dc.subjectExcited statesen_US
dc.subjectMolecular momentsen_US
dc.subjectNewton-raphson methoden_US
dc.subjectOrbital calculationsen_US
dc.subjectOxygenen_US
dc.subjectPerturbation theoryen_US
dc.subjectTransition momentsen_US
dc.subjectVibrational statesen_US
dc.subjectWateren_US
dc.titleQuadratically convergent algorithm for orbital optimization in the orbital-optimized coupled-cluster doubles method and in orbital-optimized second-order Møller-Plesset perturbation theoryen_US
dc.typeArticleen_US
dc.contributor.corporatenameGeorgia Institute of Technology. Center for Organic Photonics and Electronicsen_US
dc.contributor.corporatenameOrta Doğu Teknik Üniversitesi (Ankara, Turkey)en_US
dc.contributor.corporatenameAtatürk Üniversitesien_US
dc.contributor.corporatenameUniversity of Georgia. Center for Computational Quantum Chemistryen_US
dc.contributor.corporatenameGeorgia Institute of Technology. School of Chemistry and Biochemistryen_US
dc.contributor.corporatenameGeorgia Institute of Technology. School of Computational Science and Engineeringen_US
dc.publisher.originalAmerican Institute of Physicsen_US
dc.identifier.doi10.1063/1.3631129


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