Solvation structure of coumarin 1 in acetonitrile: role of the electrostatic solute–solvent potential

A molecular dynamics simulation study of a coumarin 1 molecule solvated in acetonitrile, in its S0 and S1 electronic states, is presented. Three solute–solvent interaction potentials, all containing the same Lennard-Jones component but different electrostatic interactions, have been considered. The structure of the solvent around the large dye solute strongly depends on the electrostatic solute–solvent potential, illustrating the crucial role of the local electric field. An accurate description of the charge distribution of the solute is therefore necessary to describe correctly the solute–solvent structure and the solvation energy.