Computing the Work of Solid-Liquid Adhesion in Systems with Damped Coulomb Interactions via Molecular Dynamics: Approaches and Insights
D Surblys and F Muller-Plathe and T Ohara, JOURNAL OF PHYSICAL CHEMISTRY A, 126, 5506-5516 (2022).
DOI: 10.1021/acs.jpca.2c03934
Recently, the dry-surface method Langmuir 2016, 31, 8335???8345 has
been developed to compute the work of adhesion of solid???liquid and
other interfaces using molecular dynamics via thermody-namic
integration. Unfortunately, when long-range Coulombic interactions are
present in the interface, a special treatment is required, such as
solving additional Poisson equations, which is usually not implemented
in generic molecular dynamics software, or as fixing some groups of
atoms in place, which is undesirable most of the time. In this work, we
replace the long-range Coulombic interactions with damped Coulomb
interactions, and explore several thermal integration paths. We
demonstrate that regardless of the integration path, the same work of
adhesion values are obtained as long as the path is reversible, but the
numerical efficiency differs vastly. Simple scaling of the interactions
is most efficient, requiring as little as 8 sampling points, followed by
changing the Coulomb damping parameter, while modifying the Coulomb
interaction cutoff length performs worst. We also demonstrate that
switching long-range Coulombic interactions to damped ones results in a
higher work of adhesion by about 10 mJ/m2 because of slightly different
liquid molecule orientation at the solid???liquid interface, and this
value is mostly unchanged for surfaces with substantially different
Coulombic interactions at the solid???liquid interface. Finally, even
though it is possible to split the work of adhesion into van der Waals
and Coulomb components, it is known that the specific per-component
values are highly dependent on the integration path. We obtain an
extreme case, which demonstrates that caution should be taken even when
restricting to qualitative comparison.
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