Conformational energetics in hydrogen-bonded dimers. The unobserved COHF complex

Abstract

Ab initio electronic-structure calculations with large basis sets and extensive treatment of electron correlation have been carried out for the COHF complex. The potential surface exhibits a local minimum for linear COHF that is over 400 cm −1 above the absolute minimum that corresponds to the OCHF structure. The main reason for the difference in the stabilities of the two conformers is the difference in their electron-correlation energies. The interconversion of COHF to OCHF follows a minimum-energy path that takes the complex through a structure where the fluorine end of HF points into the middle regions of CO.