An averaged over molecular trajectories method of integral equations of the theory of liquids in RISM approximation

A new approach for studying the influence of solvent on molecular systems is suggested. It is based on the method of integral equations in the theory of liquids in RISM approximation. We obtained a new integral equation in which the matrix of intramolecular correlations is averaged over molecular trajectories calculated by molecular dynamics method. This approach enables one to take into account the mobility of dissolved molecules in assessing the solvation effect. Using the oxytocin peptide as an example we compare the results obtained in the framework of the new method with standard calculations of thermodynamical values averaged over trajectory. It is shown that in averaging over trajectory, all the structural and thermodynamic parameters of the peptide solvation obtained by the new method lie on the interval of statistical error.