Mirón & Lebrero incorporated Plotnikov-Robinson-Jortner theory into quantum mechanical/molecular mechanical simulations to study indole in different solvents. They realised that due to the inseparability between the nuclear and electronic degrees of freedom, the effect of the solvent on the electronic component could be considered constant across a bulk with respect to different environments. As bulk simulations are in some way cast in terms of classical mechanics, Equation 39 could be instead cast as :