Mean Force Simulation of the Adsorption of Aqueous Dilute Solutions

Abstract

The adsorption from dilute solutions is of high technical importance. Convertional molecular dynamic simulations however, lead to a high degree of uncertainly in the bulk density used to calculate adsorption isotherms. To improve the sampling in the bulk the mean force method has been proposed. Within the framework of this approach the investigated particles are constrained at certain positions along a predefined reaction coordinate. The mean force method has already been used to calculate adsorption isotherms of simple mixtures as well as the solubility limit of benzene in water confined in a slit pore. However, inside the potential well the mean force deduced from the mean force approach shows larger scattering than the one from conventional molecular dynamic simulations, applying the same simulation time. This problem will be discussed in detail to improve the convergence of the mean force in the potential well.

Keywords:

• Adsorption of bio-molecules from aqueous solution
• Constrained simulation
• Mean force
• Sampling methods

ACKNOWLEDGMENT

Financial support by the Deutsche Forschungsgemeinschaft (DFG) for the project “Adsorption aus wässrigen Lösungen,” Az We 2866/1-3, within the priority research programme SPP 1155 “Molekulare Modellierung und Simulation in der Verfahrenstechnik,” as well as the allocation of computer time at the Vienna Scientific Cluster (VSC), project ID 70084 and at JUROPA (JUMP), project ID hvi020, by the John von Neumann Institute for Computing, Jülich, Germany, are gratefully acknowledged.