Naslov
Shallow-tunnelling correction factor for use with Wigner-Eyring transition-state theory

Autori
Zhang, Y.C. ; Rommel, J.B. ; Cvitaš, Marko Tomislav ; Althorpe, S.C.

Izvornik
PCCP. Physical chemistry chemical physics (1463-9076) 16 (2014), 44; 24292-24300

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

Ključne riječi
transition state theory ; instantons ; reaction rates

Sažetak
We obtain a shallow-tunnelling correction factor for use with Wigner-Eyring transition- state theory (TST). Our starting point is quantum transition state theory (QTST), which approximates the accurate quantum rate as the instantaneous flux through a delocalised transition-state ensemble of ring-polymers. Expanding the ring-polymer potential to second order gives the well-known Wigner tunnelling- factor which diverges at the cross-over temperature between deep and shallow tunnelling. Here, we show how to remove this divergence by integrating numerically over the two softest ring-polymer normal modes. This results in a modified Wigner correction factor involving a one-dimensional integral evaluated along a straight line on the potential energy surface. Comparisons with accurate quantum calculations indicate that the newly derived correction factor gives realistic estimates of quantum rate coefficients in the shallow- tunnelling regime.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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