Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/2487
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dc.contributor.authorChaudhuri, R. K-
dc.contributor.authorFreed, K. F-
dc.contributor.authorChattopadhyay, S-
dc.contributor.authorSinha Mahapatra, U-
dc.date.accessioned2008-06-23T08:58:29Z-
dc.date.available2008-06-23T08:58:29Z-
dc.date.issued2008-04-
dc.identifier.citationJ. Chem. Phys. Vol. 128, 144304en
dc.identifier.urihttp://hdl.handle.net/2248/2487-
dc.description.abstractMultireference Møller–Plesset (MRMP) perturbation theory [K. Hirao, Chem. Phys. Lett. 190, 374 (1992)] is modified to use improved virtual orbitals (IVOs) and is applied to study ground state potential energy curves for isomerization and dissociation of the N2H2 and C2H4 molecules. In contrast to traditional MRMP or multistate multiconfiguration quasidegenerate perturbation theory where the reference functions are obtained from (often difficult to converge) state averaged multiconfiguration self-consistent field methods, our reference functions are represented in terms of computationally efficient IVOs. For convenience in comparisons with other methods, a first order complete active space configuration interaction (CASCI) calculation with the IVOs is followed by the use of the IVOs in MRMP to incorporate residual electron correlation effects. The potential energy curves calculated from the IVO-MRMP method are compared with computations using state-of-the-art coupled cluster singles and doubles (CCSD) methods and variants thereof to assess the efficacy of the IVO-MRMP scheme. The present study clearly demonstrates that unlike the CCSD and its variants, the IVO-MRMP approach provides smooth and reliable ground state potential energy curves for isomerization of these systems. Although the rigorously size-extensive completely renormalized CC theory with noniterative triples corrections (CR-CC(2,3)) likewise provides relatively smooth curves, the CR-CC(2,3) calculations overestimate the cis-trans barrier height for N2H2. The ground state spectroscopic constants predicted by the IVO-CASCI method agree well with experiment and with other highly correlated ab initio methods.en
dc.format.extent193275 bytes-
dc.format.mimetypeapplication/pdf-
dc.language.isoenen
dc.publisherAmerican Institute of Physicsen
dc.relation.urihttp://link.aip.org/link/?JCPSA6/128/144304/1en
dc.rights© American Institute of Physics-
dc.subjectdissociationen
dc.subjectisomerisationen
dc.subjectground statesen
dc.subjectnitrogen compoundsen
dc.subjectorganic compoundsen
dc.subjectpotential energy surfacesen
dc.titlePotential energy curve for isomerization of N2H2 and C2H4 using the improved virtual orbital multireference Møller–Plesset perturbation theoryen
dc.typeArticleen
Appears in Collections:IIAP Publications

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