Structures, inversion barriers, and parity violation effects in chiral SeOXY molecules (X,Y=H, F, Cl, Br, or I).

Parity violation (PV) effects for a series of chiral molecules of the type SeOXY (X,Y=H, F, Cl, Br, or I) are predicted from four-component relativistic Hartree–Fock and density functional theory. All optimized SeOXY structures are nonplanar with large inversion barriers ranging from 23 to 55 kcal/mol; thus, all SeOXY molecules remain enantiomeric stable on the laboratory time scale. The variation in PV between the different methods applied is small enough for each molecule to allow for an accurate prediction of these effects. At the respective equilibrium geometries the enantiomers exhibit parity violating energy shifts of up to 17 Hz. The Se–O stretching mode of all investigated SeOXY molecules lies in the experimentally favorable CO2 laser range of ∼1000 cm-1. We therefore investigated PV effects in vibrational transitions along a single normal mode using Dirac–Kohn–Sham theory. The PV energy differences in the fundamental Se–O stretching mode amount up to 110 mHz (largest for SeOClI) and are larger compared to the C–F stretching mode of CHFBrI previously investigated. Hence these SeOXY molecules are ideal candidates for the future experimental gas-phase detection of PV in vibrational spectra of chiral molecules. [ABSTRACT FROM AUTHOR]