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dc.contributor.authorPernal, Katarzyna
dc.contributor.authorChatterjee, Koushik
dc.contributor.authorKowalski, Piotr H.
dc.date.accessioned2016-02-03T11:40:08Z
dc.date.available2016-02-03T11:40:08Z
dc.date.issued2014
dc.identifier.citationThe Journal of Chemical Physics 140, 014101 (2014)en_EN
dc.identifier.urihttp://hdl.handle.net/11652/1074
dc.identifier.urihttp://scitation.aip.org/content/aip/journal/jcp/140/1/10.1063/1.4855275
dc.description.abstractPerformance of the antisymmetrized product of strongly orthogonal geminal (APSG) ansatz in describing ground states of molecules has been extensively explored in the recent years. Not much is known, however, about possibilities of obtaining excitation energies from methods that would rely on the APSG ansatz. In the paper we investigate the recently proposed extended random phase approximations, ERPA and ERPA2, that employ APSG reduced density matrices. We also propose a time-dependent linear response APSG method (TD-APSG). Its relation to the recently proposed phase including natural orbital theory is elucidated. The methods are applied to Li2, BH, H2O, and CH2O molecules at equilibrium geometries and in the dissociating limits. It is shown that ERPA2 and TD-APSG perform better in describing double excitations than ERPA due to inclusion of the so-called diagonal double elements. Analysis of the potential energy curves of Li2, BH, and H2O reveals that ERPA2 and TD-APSG describe correctly excitation energies of dissociating molecules if orbitals involved in breaking bonds are involved. For single excitations of molecules at equilibrium geometries the accuracy of the APSG-based methods approaches that of the time-dependent Hartree-Fock method with the increase of the system size. A possibility of improving the accuracy of the TD-APSG method for single excitations by splitting the electron-electron interaction operator into the long- and short-range terms and employing density functionals to treat the latter is presented.en_EN
dc.language.isoenen_EN
dc.publisherAmerican Institute of Physicsen_EN
dc.relation.ispartofseriesThe Journal of Chemical Physics 140, 2014en_EN
dc.titleHow accurate is the strongly orthogonal geminal theory in predicting excitation energies? Comparison of the extended random phase approximation and the linear response theory approachesen_EN
dc.typeArtykułpl_PL
dc.typeArticleen_EN
dc.identifier.doidoi: 10.1063/1.4855275


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