Enhancement of the parity-violating energy difference of H2X2 molecules by electronic excitation

Abstract

The parity-violating energy difference (PVED) between two enantiomers of a chiral molecule is caused by the weak interaction. Because of the smallness of the PVED, nonzero PVED is yet to be discovered in experimental searches. To detect the PVED, the search for molecules with large PVED values is important. Previously, one of the authors proposed that the PVED may be significantly enhanced in ionized or excited states. The significant enhancement of the PVED in some electronic excited states is proven in this study using H 2 X 2 (X = O, S, Se, Te) molecules as examples. The maximum enhancement was an about 360-fold increase for H 2 Se 2 . For the PVED calculation, we employ the finite-field perturbation theory (FFPT) within the equation-of-motion coupledcluster theory based on the exact two-component molecular mean-field Hamiltonian. The relation between the enhancement of the PVED and the contribution to the PVED from the highest occupied molecular orbital is also examined. The effects of computational elements, such as parameters related to the electron correlation and FFPT on PVED values in excited states of H 2 X 2 molecules, are studied.

Chiral selectivity vs. noise in spontaneous mirror symmetry breaking

“…21,22 In the domain of fundamental physics, violation of charge-parity (CP) symmetry determines that enantiomorphs are non-identical entities by virtue of the tiny energy difference that exists between them. 8,[23][24][25][26][27][28][29][30][31] Although PVED has not yet been detected in typical chemical experiments 29,30,[32][33][34] a logical connection exists between physical reality and biological chirality. 35,36 However, the planned design and construction of ultrahigh resolution instruments for vibrational spectra, and the use of heavy atom chiral complexes, promises the possibility of successful PVED measurements being carried out in the near future.…”