Strongly correlated barriers to rotation from parametric two-electron reduced-density-matrix methods in application to the isomerization of diazene

Andrew M. Sand, Christine A. Schwerdtfeger, David A. Mazziotti

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28 Scopus citations

Abstract

Recently, parameterization of the two-electron reduced density matrix (2-RDM) has made possible the determination of electronic energies with greater accuracy and lower cost than traditional electron-pair theories including coupled cluster with single and double excitations [D. A. Mazziotti, Phys. Rev. Lett. 101, 253002 (2008)]. We examine the methods performance for strongly correlated barriers to rotation; in particular, we study two distinct pathways in the isomerization of diazene (N 2H 2) from cis to trans: (i) a strongly correlated rotational pathway and (ii) a moderately correlated inversion pathway. While single reference wavefunction methods predict that the rotational barrier is higher than the inversional barrier, the parametric 2-RDM method predicts that the rotational barrier is lower than the inversional barrier by 3.1 kcal/mol in the extrapolated basis set limit. The parametric 2-RDM results are in agreement with those from multireference methods including multireference perturbation theory and the solution to the anti-Hermitian contracted Schrdinger equation. We report energies, optimized structures, and natural orbital occupation numbers for three diazene minima and two transition states.

Original languageEnglish (US)
Article number034112
JournalJournal of Chemical Physics
Volume136
Issue number3
DOIs
StatePublished - Jan 21 2012

Bibliographical note

Funding Information:
D.A.M. gratefully acknowledges the NSF, the ARO, the Henry-Camille Dreyfus Foundation, the David-Lucile Packard Foundation, and the Microsoft Corporation for their support.

Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.

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