Ab Initio Molecular Dynamics Simulation of Liquid Water: Three Gradient-Corrected Density Functionals Compared

Three frequently used gradient-corrected density functionals (B, BP and BLYP) are applied in an {\it ab initio} molecular dynamics simulation of liquid water in order to evaluate their performance for the description of condensed aqueous systems. A comparison of structural characteristics (radial distribution functions) and dynamical properties (vibrational spectra, orientational relaxation, and self-diffusion) leads to the conclusion that hydrogen bonding is too weak in the usual local density approximation corrected for exchange only according to Becke (B), whereas adding the gradient correction for correlation according to Perdew (BP) yields effective hydrogen bonds in the liquid that are too strong. The combination of B with the semilocal correlation functional according to Lee, Yang, and Parr (BLYP) yields the best agreement with experiment. The computational method, which is the basis for the determination of (adiabatic) electronic structure in the {\it ab initio} molecular dynamics simulation, has been validated by an extensive series of test calculations for the water dimer, which will also be presented here.