Inclusion of cybotactic effect in the theoretical modeling of absorption spectra of liquid-state systems with perturbed matrix method and molecular dynamics simulations: the UV–Vis absorption spectrum of para-nitroaniline as a case study

In this study, we present an extension of the theoretical-computational approach developed in our group and based on molecular dynamics simulations, quantum chemical calculations, perturbed matrix method, and essential dynamics analysis for taking into account the cybotactic effect in the computational modeling of absorption spectra of molecular systems in condensed phase. The low-energy UV-Vis spectra of para-nitroaniline in water, methanol, and in the presence of a zwitterionic micelle have been computationally addressed and compared to the experimental data. The approach, considering all the systematic errors deriving from the intrinsic limitations of the computational setup (force field, quantum chemical calculations, and the approximations of the method), satisfactorily reproduces the experimental spectral shifts and peaks shapes and provides a promising tool of investigation for reproducing spectral observables of very complex systems.