Volume 113, Issue 15, 15 October 2000
Index of content:
Construction of an accurate potential energy surface by interpolation with Cartesian weighting coordinates113(2000); http://dx.doi.org/10.1063/1.1315348View Description Hide Description
A modified method to construct an accurate potential energy surface by interpolation is presented. The modification is based on the use of Cartesian coordinates in the weighting function. The translational and rotational invariance of the potential is incorporated by a proper definition of the distance between two Cartesian configurations. A numerical algorithm to find the distance is developed. It is shown that the present method is more exact in describing a planar system compared to the previous methods with weightings in internal coordinates. The applicability of the method to reactive systems is also demonstrated by performing classical trajectory simulations on the surface.
113(2000); http://dx.doi.org/10.1063/1.1315991View Description Hide Description
Dielectric relaxation of water for a wide range of temperature and density is studied with the molecular dynamics simulation technique. The evolving water electronic structure is explicitly incorporated via the truncated adiabatic basis-set representation. For a given density, polarization dynamics of water tends to become faster with increasing temperature. At reduced densities, it shows a marked deviation from a single exponential decay. Another interesting feature is that at fixed T, water dielectric relaxation becomes, in general, accelerated as the density decreases. This trend is at variance with recent microwave spectroscopymeasurements at elevated temperatures and reduced densities. Possible sources for the discrepancy between the simulation and experimental results are discussed.