Fast generation of nonresonant and resonant optical rotatory dispersion curves with the help of circular dichroism calculations and Kramers-Kronig transformations

It can be computationally expensive to compute smooth, well resolved, optical rotation (OR) dispersion (ORD) curves from first principles theory. Instead of computing the OR at a large number of frequency points, similar results can be obtained by combined use of a computed circular dichroism (CD) spectrum along with a few OR calculations by using subtractive Kramers-Kronig transformations. We have tested various subtractive schemes for simulated (analytical) CD/ORD and for time-dependent density functional computations for dimethyloxirane, fenchone, and [4]triangulane. Non-resonant ORD can be obtained with as few as two OR and one CD calculation. For resonant ORD we found that between 7 and 15 OR computations plus the CD spectrum were typically sufficient, depending on the number of excitations within the frequency window of interest.