DETERMINATION OF FORCE-FIELD PARAMETERS FOR MOLECULAR SIMULATION BY MOLECULAR SIMULATION - AN APPLICATION OF THE WEAK-COUPLING METHOD

A method for automatic adjustment of force field parameters to known liquid properties is described. The method works by coupling the time derivative of the force field parameter to the deviation of the actual value of the observable from prescribed reference value. The method is generally applicable, if (i) a strong relationship between a parameter and an observable exists, and (ii) if this relationship is monotonie within the convergence interval of the parameter. The method is applied to the Lennard-Jones potential energy function. It is shown computationally that it is feasible to couple the Lennard-Jones ∈ parameter to the heat of vaporization or to the chemical potential, and the Lennard-Jones σ parameter to the pressure or the diffusion coefficient of a liquid. It is also shown that it is possible to couple simultaneously two parameters to two observables. With the range of applicability established, the technique is then tested on liquid mercury. © 1995 American Institute of Physics.