Molecular second-quantized Hamiltonian: Electron correlation and non-adiabatic coupling treated on an equal footing

Marat Sibaev*, Iakov Polyak, Frederick R. Manby, Peter J. Knowles

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

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Abstract

We introduce a new theoretical and computational framework for treating molecular quantum mechanics without the Born–Oppenheimer approximation. The molecular wavefunction is represented in a tensor-product space of electronic and vibrational basis functions, with electronic basis chosen to reproduce the mean-field electronic structure at all geometries. We show how to transform the Hamiltonian to a fully second-quantized form with creation/annihilation operators for electronic and vibrational quantum particles, paving the way for polynomial-scaling approximations to the tensor-product space formalism. In addition, we make a proof-of-principle application of the new Ansatz to the vibronic spectrum of C2.
Original languageEnglish
Article number124102
Number of pages15
JournalJournal of Chemical Physics
Volume153
Issue number12
DOIs
Publication statusPublished - 28 Sep 2020

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