WATER DIMER PROPERTIES IN THE GRADIENT-CORRECTED DENSITY FUNCTIONAL THEORY

Using a gradient-corrected version of the local density approximation to the energy density functional we calculate the structural properties of the water dimer. We find that without gradient corrections the local density approximation gives realistic results for the intramolecular properties, but fails to give a correct description of the intermolecular interactions and the binding properties. Such defects can be remedied with the inclusion of the gradient corrections. The resulting dimer properties are in good agreement with more sophisticated quantum chemical calculations. The calculation has been performed using a plane wave expansion and a pseudopotential scheme. Thus it can be used to perform realistic Car-Parrinello-like molecular dynamics simulations of water.