Cavity field effects within a polarizable continuum model of solvation: application to the calculation of electronic circular dichroism spectra of R-(+)-3-Methyl-cyclopentanone

The effect of the cavity field (CF) on electronic circular dichroism spectra simulated using a polarizable continuum model (PCM) is analyzed. The difference between classical and effective electric field, arising from the charges induced on the surface of the cavity by the radiation field, is shown to have a nonnegligible effect on the rotatory strengths computed within a TDDFT PCM in the case of R-(+)-3-methylcyclopentanone, a chiral molecule whose ECD spectrum, both in the gas and in several solvents, has been studied both experimentally and theoretically in recent times. PCM CF factors are on the order of 10% smaller than predicted by the Onsager model for the lowest, S1 excited state, in the two conformers known to accommodate almost the whole population at room temperature, in the gas phase and in solution. The percentage increases quite substantially for the second, S2 excited electronic state. In PCM, CF factors are not merely scalar multiplicative factors for the gas-phase rotational strengths. Instead, they show an anisotropy along the axes of the cavity—a consequence of the adoption of nonspherical cavities.