Study of tunnelling in symmetrical double-Morse hydrogen bonds via the instanton-soliton approach: large polarizability and isotopic effect

Abstract

An explicit expression for the energy splitting due to tunnelling in a symmetric double-Morse potential was derived within the instanton-soliton approach to Feynman's path integral formalism and to first order with regard to Planck's constant. Different formulae for the energy splitting in terms of the dissociation constant, the barrier height, the barrier thickness, and the classical frequency of the transition state are also presented. The formula obtained was applied to study the concept of large proton polarizability and the large isotopic effect of proton tunnelling in symmetrical homoconjugated hydrogen bonds.