Naslov
Which Is Better at Predicting Quantum-Tunneling Rates: Quantum Transition-State Theory or Free- Energy Instanton Theory?

Autori
Zhang, Y.C. ; Stecher, T. ; Cvitaš, Marko Tomislav ; Althorpe, S.C.

Izvornik
Journal of Physical Chemistry Letters (1948-7185) 5 (2014), 22; 3976-3980

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
instanton ; quantum transition state theory ; tunneling ; reaction rates

Sažetak
Quantum transition-state theory (QTST) and free-energy instanton theory (FEIT) are two closely related methods for estimating the quantum rate coefficient from the free-energy at the reaction barrier. In calculations on one-dimensional models, FEIT typically gives closer agreement than QTST with the exact quantum results at all temperatures below the crossover to deep tunneling, suggesting that FEIT is a better approximation than QTST in this regime. Here we show that this simple trend does not hold for systems of greater dimensionality. We report tests on several collinear and three-dimensional reactions, in which QTST outperforms FEIT over a range of temperatures below crossover, which can extend down to half the crossover temperature (below which FEIT outperforms QTST). This suggests that QTST-based methods such as ring-polymer molecular dynamics (RPMD) may often give closer agreement with the exact quantum results than FEIT.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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