Calculation of the parity nonconserving energy difference between mirror-image molecules

Abstract

The theory of energy shifts in mirror‐image molecules arising from parity nonconserving weak neutral currents is developed. Its connection with the theory of optical activity is discussed. In order to demonstrate the existence of the energy shift, which produces an energy difference between an optically active molecule and its mirror image, an exact calculation is performed for a simple one‐electron model (the Condon model). Then approximate LCAO‐MO calculations are performed on two specific molecules, twisted ethylene and A‐nor‐2‐thiacholestane, in order to obtain more reliable order‐of‐magnitude estimates of the energy shifts than available previously. According to our calculations, the former molecule has an energy shift two orders of magnitude larger than the latter, but both molecules have energy shifts which are appreciably smaller than the previous estimates.