Molecular dynamics simulations of wetting and drying in LJ models of solid-fluid interfaces in the presence of liquid-vapour coexistence

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Abstract
The structure and phase behaviour of adsorbed films is modelled by cut and shifted LJ fluid in the presence of cut and shifted 9-3 walls. At fixed N, it is straightforward to use molecular dynamics simulation procedures to study planar adsorbed films in the presence of ‘bulk’ liquid-vapour coexistence. A series of five isotherms are investigated in detail, ranging from temperatures close to the bulk triple point to a little over half way to the critical point. As a by-product, accurate data are obtained for liquid-vapour coexistence properties and surface tensions of cut and shifted LJ fluid. Wall-fluid excess grand potentials are calculated and compared with the predictions of weighted density functional theory. Isotherms of contact angle against wall-fluid attractive interaction strength are given, each covering the entire region from complete drying to complete wetting. The dynamics of wetting transitions is not accessible in our geometry. In contrast, the presence of a suitable collective mode enables transitions to complete drying to be directly observed by molecular dynamics simulation in planar symmetry. Overall, we find a remarkable similarity with the results of previous projects based on square-well models of atomic matter.

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