Hai Hoang, Sangmo Kang, Yong Kweon Suh
The Journal of Mechanical Science and Technology, vol. 24, no. 7, pp.1401-1410, 2010

Abstract : We numerically investigate the effect of the solution-wall (i.e., water-wall and ion-wall) interaction potential on the properties of confined aqueous solution by using molecular dynamics (MD) simulations. The effect is determined by comparing results obtained from the MD simulation using the Lennard-Jones (L-J) potential for the water-wall and ion-wall interactions and those using a purely repulsive potential, i.e., the Weeks-Chandler-Andersen-like potential. In the MD simulations, 680 water molecules and 20 chloride ions are included between uniformly charged plates that are separated by 2.6 nm. The results show that the properties of solution are influenced only in the region close to the wall: The water molecules are more densely packed for the case of the L-J potential. Comparison of the results of the MD simulations in the case of the L-J potential with those provided by solving the Poisson-Boltzmann equation, we found that classical continuum theory fails to predict the ion density and electrostatic potential distributions in the region near to the wall, but far way from the wall, the prediction from the continuum theory is in line with the MD simulation.

Keyword : Molecular dynamics simulation; Aqueous solution; Hydrophobic plate; WCA potential; PPPM methods