Electroweak interactions in chiral molecules: two-component density functional theory study of vibrational frequency shifts in polyhalomethanes

摘要

In this paper, a two-component density functional theory study of parity violation-induced vibrational frequency shifts in chiral polyhalomethanes is reported and the prospects to detect in these compounds, for the first time, signals of parity violation in molecular systems are discussed. The recent synthesis of enantiomerically enriched CHC1FI has renewed interest in examining electroweak corrections for this class of compounds. Utilizing a (quasi-relativistic) two-component zeroth-order regular approximation approach to molecular parity violation, together with density functional theory, the parity violation-induced relative vibrational frequency splittings Delta v(pv)/v between the C-F stretching fundamental of polyhalomethane enantiomers are computed. The relative splitting in CHC1FI is raised compared with CHBrC1F, for which upper bounds were determined experimentally. To facilitate measurement, molecules possessing more pronounced relative splittings are desirable. Therefore, the chiral methane derivative CHAtFI is considered, which exhibits a significantly larger electroweak contribution that induces a vibrational frequency splitting on the order of the experimental resolution previously reported for CHBrC1F. Employing compounds containing heavy nuclei such as astatine may thus be necessary with present detection methods.