PNNL

Abstract

We present a comprehensive set of results for water, a case study of a hydrogen-bonded system, using the self-consistent polarization density functional theory (SCP-DFT). With minimal parametrization, SCP-DFT is found to give good results for the interaction energy of the dimer; the geometries, cohesion energies, and harmonic frequencies of larger clusters; and the structure and enthalpy of the liquid, as compared to accurate theoretical and experimental benchmarks. We also compared our SCP-DFT potential to the base DFT BLYP potential and also to a simpler dispersion-supplemented potential, BLYP-D. Using the symmetry-adapted perturbation theory (with a DFT description of monomers), the BLYP, BLYP-D, and SCP-DFT water dimer potentials were analyzed into their physically interpretable components. Comparison with the benchmark SAPT(DFT) components showed reasonable agreement for all the four components of electrostatics, exchange, induction, and dispersion energies. This procedure enhances understanding and can suggest further improvements. Thus, the SCP-DFT approach holds promise as a fast, efficient, and accurate method for performing ab initio dynamics that include additional polarization and dispersion interactions for large, complex systems involving solvation and bond breaking.