A hybrid classical-quantum algorithm to simulate ECD spectra – the case of tryptophan zwitterions in water

Abstract

The vibronic structure of electronic circular dichroism (ECD) spectra is simulated in silico using a hybrid method that encompasses ab initio time-dependent density functional theory (TD-DFT) calculations and the Doktorov quantum algorithm. Four low-energy electronic excitations of the chiral tryptophan amino acid are characterized and their spectra are simulated with and without considering the Duschinsky rotation effects. The normal mode mixing shows a very small impact on the vibronic structure. Moreover, it demonstrates the versatility of the quantum algorithm to focus on individual normal mode contributions to the vibronic structure of the spectrum.