Umbrella Sampling Method Research Articles

Calculation of free energy differences for water from computer simulations

Free energy differences for water at different temperatures have been calculated from Monte Carlo computer simulations using both ratio overlap and umbrella sampling methods. The problems of calculating precise values from these methods are discussed. Three models for water (ST2, TIPS2 and PE) have been used in these calculations which have been compared with experimental estimates for the configurational free energy. The importance of being able to predict accurate mean potential energies as well as accurate energy distributions is emphasised.

Excess free energy of different water models computed by Monte Carlo methods

The excess free energy and entropy of three water models (ST2, MCY and SPC) are determined using Monte Carlo thermodynamic integration, with soft spheres as a reference system. The method used is compared with two other methods, the umbrella sampling and the overlap ratio methods. A simple self check for the umbrella sampling method is proposed.