Empirical force fields, electronic polarization

Keywords Empirical force field, Electronic polarization, Polarizability, Force field, Inducible dipoles,... 

The utility of CP dynamics is that it allows one to follow the electronic structure throughout the course of the simulation. This is not the case when empirical force fields are used. One simple property that can be evaluated throughout the CP liquid water simulation is the average dipole moment of a water molecule. The value extracted from these simulations, 2.66 D, is in good agreement with their cited experimental value of 2.6 Within CP dynamics, polarization of the water molecules (their gas phase dipole moment is 1.85 D) is automatically achieved, bypassing the parameterization process that use of a polarizable, nonadditive force field would entail. The ab initio molecular dynamics simulation also allowed them to follow the nature the lowest unoccupied molecular orbital (LUMO) which plays a role in the conduction of an excess electron. 

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