Efficient protocol for quantum Monte Carlo calculations of hydrogen abstraction barriers: Application to methanol

Ellen T. Swann, Michelle L. Coote, Amanda S. Barnard, Manolo C. Per*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    11 Citations (Scopus)

    Abstract

    Accurate calculation of hydrogen abstraction reaction barriers is a challenging problem, often requiring high level quantum chemistry methods that scale poorly with system size. Quantum Monte Carlo (QMC) methods provide an alternative approach that exhibit much better scaling, but these methods are still computationally expensive. We describe approaches that can significantly reduce the cost of QMC calculations of barrier heights, using the hydrogen abstraction of methanol by a hydrogen atom as an illustrative example. By analysing the combined influence of trial wavefunctions and pseudopotential quadrature settings on the barrier heights, variance, and time-step errors, we devise a simple protocol that minimizes the cost of the QMC calculations while retaining accuracy comparable to large-basis coupled cluster theory. We demonstrate that this protocol is transferable to other hydrogen abstraction reactions.

    Original languageEnglish
    Article numbere25361
    JournalInternational Journal of Quantum Chemistry
    Volume117
    Issue number9
    DOIs
    Publication statusPublished - 5 May 2017

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