On the importance of configurational sampling in theoretical calculation of electronic properties of complex molecular systems: Acetone in water

In this work, we address the problem of the role and relevance of the aqueous environment configurational sampling on acetone electronic properties: the (vertical) absorption spectrum and corresponding excitation Helmholtz free energy. By comparing the results obtained by applying the perturbed matrix method (PMM) on molecular dynamics (MD) trajectories of different sampling efficiency, we specifically quantify the effects of the phase space sampling on acetone vertical electronic excitations. Results confirm that PMM provides an accurate and physically consistent description of the electronic excitation processes and show the crucial importance of an extended configurational sampling of the solvent environment in order to obtain a reliable (chromophore) absorption behaviour.