A Two-Scale Approach to Electron Correlation in Multiconfigurational Perturbation Theory

Farahani, Pooria,1985-Uppsala universitet,Teoretisk kemi,Theoretical Chemistry programme (författare)

QC 20171004. QC 20200713
We present a new approach for the calculation of dynamicelectron correlation effects in large molecular systems usingmulticonfigurational second-order perturbation theory(CASPT2). The method is restricted to cases where partitioningof the molecular system into an active site and an environment is meaningful. Only dynamic correlation effects derivedfrom orbitals extending over the active site are included at theCASPT2 level of theory, whereas the correlation effects of theenvironment are retrieved at lower computational costs. Forsufficiently large systems, the small errors introduced by thisapproximation are contrasted by the substantial savings inboth storage and computational demands compared to thefull CASPT2 calculation. Provided that static correlation effectsare correctly taken into account for the whole system, the proposed scheme represent a hierarchical approach to the electron correlation problem, where two molecular scales aretreated each by means of the most suitable level of theory.

Roca-Sanjuán, DanielUniversitat de València, Spain,Instituto de Ciencia Molecular (författare)
Aquilante, FrancescoUppsala universitet,Teoretisk kemi,Università di Bologna, Italy,Dipartimento di Chimica(Swepub:uu)fraaq368 (författare)
Uppsala universitetTeoretisk kemi (creator_code:org_t)

Ingår i:Journal of Computational Chemistry: John Wiley & Sons35:22, s. 1609-16170192-86511096-987X

Av författaren/redakt...: Farahani, Pooria ...; Roca-Sanjuán, Da ...; Aquilante, Franc ...

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