On simulations of complex interfaces: molecular dynamics simulations of stationary phases

Methodological considerations for molecular dynamics simulations of complex interfaces are presented in this article. A slab geometry is examined in the context of stationary phases where selectivity occurs predominantly in pores within silica beads. Specifically, we examine the Whelk-O1 interface with n-hexane/2-propanol, the TMA-(Pro)(2)-N(CH(3))-tether interface with n-hexane/2-propanol, and the C(18)H(37)Si interface with water/methanol. The following methodological issues are considered in detail: The assessment of solvent density within the confined region and excluded volume of the interface; the structural equilibration of surface-bound moieties; solvent equilibration for binary mixtures; surface size effects, and periodic boundary conditions; the treatment of electrostatic interactions; and the impact of pore size.