Exchange repulsion increases internal rotation floppiness

摘要

The influence of antisymmetrization (exchange repulsion) on the shape of internal rotation potential surfaces is investigated by comparing potential curves with and without antisymmetrization. The ab initio 6-311G(3df,2p) and 6-311G++(3df,2p) calculations show that exchange interaction, for the three ethane-family molecules (ethane, dislane, and methanol) investigated, increases the torsional amplitude and level splittings. An outcome of the exchange repulsion-triggered lowered torsional frequencies is increase in excited torsional level populations with consequent effect on thermodynamic and spectroscopic properties.