Simple method to modify force fields for the molecular dynamics simulation of aqueous solutions

We propose a simple method to modify force field parameters in the molecular dynamics simulation of aqueous solutions of alcohols at concentration changes. On the example of methanol, ethanol, 1- and 2-propanol the description of the experimental density of solutions is significantly improved as compared with the use of the OPLS-AA standard force field. It is shown that to this end, it is enough to change charges on alcohol molecules linearly with the concentration. Bulk characteristics of solutions are calculated for the obtained models, and they are well consistent with the experimental ones. In particular, it is possible to quantitatively reproduce minima on the curves of apparent and partial molar volumes characteristic of considered alcohols in the region of low concentrations.