Study of the structure of molecular complexes. VII. Effect of correlation energy corrections to the Hartreehyphen;Fock waterhyphen;water potential on Monte Carlo simulations of liquid water

摘要

The twohyphen;body Hartreehyphen;Fock potential for waterhyphen;water interactions previously used to describe small water clusters and used in Monte Carlo studies of liquid water has been used to assess the effect of neglecting the correlation energy correction. A number of semiempirical corrections based on the London, Kirkwood, and Wigner formulas were used. They have an energy spread such that they encompass the expected magnitude of the exact correlation energy correction. Short range correlation interactions were included using a modification of the functional of density proposed by Wigner and the corresponding long range interactions were given by a term proportional torminus;6with coefficients due to both London and Kirkwood. After adding the corrections to the Hartreehyphen;Fock potential the various potentials were compared by generating a number of potential energy surfaces. Following this the waterhyphen;water potentials were used in a Monte Carlo simulation of liquid water to calculate thermodynamic and structural data. After comparing the results with experimental data it is seen that the Hartreehyphen;Fock potential gives a realistic representation of the structure of liquid water but predicts poor thermodynamic data. Correlation energy corrections reduce the discrepancies significantly and it is probable that the remaining error is attributable to manyhyphen;body effects. The potentials are sufficiently accurate that certain discrepancies in the interpretation of scattering data for liquid water can be indicated.