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dc.contributor.authorYost, Shane R. ( )
dc.contributor.authorHead-Gordon, Martin ( )
dc.date.accessioned2019-08-20T21:52:37Z
dc.date.available2019-08-20T21:52:37Z
dc.date.issued2018-07
dc.identifier.citationYost, S. R., & Head-Gordon, M. (2018). Efficient Implementation of NOCI-MP2 Using the Resolution of the Identity Approximation with Application to Charged Dimers and Long C-C Bonds in Ethane Derivatives. Journal of Chemical Theory and Computation, 14(9), pp. 4791–4805.en_US
dc.identifier.urihttps://digital.library.txstate.edu/handle/10877/8534
dc.description.abstractAn efficient implementation of the perturb-then-diagonalize nonorthogonal configuration interaction method with second-order Møller-Plesset perturbation theory (NOCI-MP2) is presented. Relative to other low scaling multireference perturbation theories, NOCI-MP2 often requires a much smaller active space because of the use of nonorthogonal reference configurations. Reworking the NOCI-MP2 equations with the resolution of the identity (RI) approximation enables the method to have the same memory requirements and computational scaling as single reference RI-MP2. The working equations are extended to include single substitutions as required when the reference determinants do not satisfy the Hartree-Fock equations. A detailed computational algorithm is presented along with timings to establish the performance of the implementation. NOCI-MP2 is applied to the binding energy and charge resonance energy in dication and monocation π dimers, as well as didiamantane ethane, and hexaphenylethane. A well-defined set of nonorthogonal determinants are obtained using absolutely localized molecular orbitals (ALMOs), as solutions to the self-consistent field for molecular interactions (SCF-MI) equations corresponding to covalent and ionic determinants. Agreement with experimental information where available, and other multireference methods, is satisfactory, with the use of an 0.3 au level shift to guard against large MP2 amplitudes. For didiamantane ethane and hexaphenylethane, large dispersion forces help stabilize the molecules despite the steric repulsion. By contrast, in the case of hexaphenylethane, the energy penalty from the geometric distortion of the fragments significantly weakens the bond.en_US
dc.formatText
dc.format.extent57 pages
dc.format.medium1 file (.pdf)
dc.language.isoen
dc.publisherAmerican Chemical Societyen_US
dc.sourceJournal of Chemical Theory and Computation, 2018, Vol. 14, No. 9, pp. 4791–4805
dc.subjectNOCI-MP2
dc.subjectRI-MP2
dc.subjectEthane derivatives
dc.titleEfficient Implementation of NOCI-MP2 Using the Resolution of the Identity Approximation with Application to Charged Dimers and Long C-C Bonds in Ethane Derivativesen_US
dc.typeacceptedVersion
txstate.documenttypeArticle
dc.description.versionThis is the accepted manuscript version of an article published in Journal of Chemical Theory and Computation.
dc.identifier.doihttps://doi.org/10.1021/acs.jctc.8b00697
txstate.departmentChemistry and Biochemistry


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