A molecular dynamics study of the evolution from the formation of the {\text {C}}_{6}{\text {F}}_{6}–({\text {H}}_{2}{\text {O}})_{n} small aggregates to the {\text {C}}_{6}{\text {F}}_{6} solvation

The interaction between hexafluorobenzene, \({\text {C}}_{6}{\text {F}}_{6}\), and \({\text {H}}_{2}\)O is investigated to construct a force field for molecular dynamics simulations. In order to construct the \({\text {C}}_{6}{\text {F}}_{6}\)–\({\text {H}}_{2}\)O intermolecular interaction function, the nonpermanent charge contributions, grouped in the so-called nonelectrostatic term and described using an improved Lennard-Jones model, are combined with the electrostatic energy calculated in agreement with the permanent electric quadrupole and dipole moments of \({\text {C}}_{6}{\text {F}}_{6}\) and \({\text {H}}_{2}\)O, respectively. Moreover, to test the potential energy function, BSSE-corrected energies at CCSD(T)/aug-cc-pVTZ level are calculated for three different approaches of \({\text {H}}_{2}{\text {O}}\)–\({\text {C}}_{6}{\text {F}}_{6}\). By using the constructed force field, the structure and energetics of some small aggregates [\({\text {C}}_{6}{\text {F}}_{6}\)–(\({\text {H}}_{2}{\text {O}})_{n}\) (\(n= 1{\text {--}}6\))], the formation of the first solvation shell [\({\text {C}}_{6}{\text {F}}_{6}\)–(\({\text {H}}_{2}{\text {O}})_{n}\) (\(n = 9{\text {--}}36\))] and the solvation of \({\text {C}}_{6}{\text {F}}_{6}\) by 400 molecules of \({\text {H}}_{2}\)O have been investigated. The \({\text {C}}_{6}{\text {F}}_{6}\)–(\({\text {H}}_{2}{\text {O}})_{n}\) (\(n= 1{\text {--}}6\)) small aggregates and the formation of the first solvation shell have been simulated using a microcanonical (NVE) ensemble of particles, while an isobaric–isothermal ensemble (NpT) has been used to investigate the solvation of \({\text {C}}_{6}{\text {F}}_{6}\). Moreover, in order to approximate the system formed by one \({\text {C}}_{6}{\text {F}}_{6}\) and 400 \({\text {H}}_{2}\)O molecules to a large (infinite) system, periodic boundary conditions have been imposed in the simulation of the solvation of \({\text {C}}_{6}{\text {F}}_{6}\).