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

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
Number of pages7
JournalInternational Journal of Quantum Chemistry
Volume117
Issue number9
DOIs
Publication statusPublished - 5 May 2017
Externally publishedYes

Keywords

  • methanol
  • quantum Monte Carlo
  • reaction barrier

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