A hybrid density functional classical molecular dynamics simulation of a water molecule in liquid water

A hybrid NVE Molecular Dynamics simulation of liquid water is presented using a coupled Density Functional/Molecular Mechanics hamiltonian. The quantum subsystem is a single water molecule described by means of a triple-zeta quality basis set with polarization orbitals on oxygen and hydrogen atoms. Non-local exchange-correlation corrections are included self-consistently. The classical system is constituted by 128 TIP3P water molecules. Results are in reasonable agreement with experimental data and in particular a good description of the solute polarization is obtained. Large fluctuations of the instantaneous value of the dipole moment of the quantum molecule are predicted.