2018/05/07 by Gabriel Laude, Danilo Calderini, Laude, Gabriel +5 · 3 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #Atmospheric Ozone and Climate #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Spectroscopy and Laser Applications
paper · pdf · doi:10.48550/arxiv.1805.02589
openalex publication_date 2018/05/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Ab initio instanton rate theory is a computational method for rigorously\nincluding tunnelling effects into calculations of chemical reaction rates based\non a potential-energy surface computed on the fly from electronic-structure\ntheory. This approach is necessary to extend conventional transition-state\ntheory into the deep-tunnelling regime, but is also more computationally\nexpensive as it requires many more ab initio calculations. We propose an\napproach which uses Gaussian process regression to fit the potential-energy\nsurface locally around the dominant tunnelling pathway. The method can be\nconverged to give the same result as from an on-the-fly ab initio instanton\ncalculation but requires far fewer electronic-structure calculations. This\nmakes it a practical approach for obtaining accurate rate constants based on\nhigh-level electronic-structure methods. We show fast convergence to reproduce\nbenchmark H + CH4 results and evaluate new low-temperature rates of H + C2H6 in\nfull dimensionality at a UCCSD(T)-F12b/cc-pVTZ-F12 level.\n