Toward Accurate Hydrogen Bonds by Scalable Quantum Monte Carlo

Single-determinant (SD) fixed-node diffusion Monte Carlo (FNDMC) gains popularity as a benchmark method scalable to large noncovalent systems, although its accuracy limits are not yet fully mapped out. We report on an interesting example of significant SD FNDMC accuracy variations in middle-sized hy...

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Bibliographic Details
Published in:Journal of chemical theory and computation 2019-06, Vol.15 (6), p.3552-3557
Main Authors: Dubecký, Matúš, Jurečka, Petr, Mitas, Lubos, Ditte, Matej, Fanta, Roman
Format: Article
Language:English
Subjects:
Accuracy
Benchmarks
Dimers
Formic acid
Hydrogen bonding
Hydrogen bonds
Systematic errors
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Summary:Single-determinant (SD) fixed-node diffusion Monte Carlo (FNDMC) gains popularity as a benchmark method scalable to large noncovalent systems, although its accuracy limits are not yet fully mapped out. We report on an interesting example of significant SD FNDMC accuracy variations in middle-sized hydrogen-bonded dimer complexes, formic acid (FA) vs methanediol (MD), distinct by the maximum bond order (2 vs 1). While the traditional SD FNDMC schemes based on bias cancellation are capable of achieving benchmark (2%) accuracy for MD, this has not been the case for FA. We identify the leading systematic error source in energy differences and show that suitably designed Jastrow factors enable SD FNDMC to reach the reference accuracy for FA. This work clearly illustrates the varying accuracy of the present-day SD FNDMC at the 0.1 kcal/mol scale for a particular set of systems but also points out promising routes toward alleviation of these shortcomings, still within the single-reference framework.
ISSN:1549-9618
1549-9626
DOI:10.1021/acs.jctc.9b00096