A new scheme to calculate isotope effects
We present a new scheme to calculate isotope effects. Only selected frequencies at the target level of theory are calculated. The frequencies are selected by an analysis of the Hessian from a lower level of theory. We obtain accurate isotope effects without calculating the full Hessian at the target level of theory. The calculated frequencies are very accurate. The scheme converges to the correct isotope effect.
isotope effects computational chemistry molecular modeling