Browsing by Author "Chouksey, Shubham"

We study the molecular-scale features of the solid surface that result in the spontaneous motion of a nanodroplet due to the periodic variation of temperature. We first employ a thermodynamic model to predict the variation of solid–fluid interfacial properties that can result in the above motion. The model identifies a composite (surface couple) made of two surfaces that are characterised by a large difference between the entropic parts of the solid–liquid interfacial free energies. In order to understand the molecular-scale features of the two surfaces that may form a surface couple, we performed grand canonical Monte Carlo simulations of Lennard Jones fluid and crystalline surfaces made of Lennard Jones-like atoms. We then used the cumulant expansions of the perturbation formulas to divide the interfacial entropy into two parts: The one that is directly affected by the solid–fluid attraction (direct part), and the other (indirect part) that is indirectly affected by the solid–fluid attraction via the alteration of interfacial fluctuations. Our results indicate that two surfaces form a surface couple if the differences between their chemical natures lead to large differences in the indirect part of the interfacial entropy, while the direct part remains relatively unaffected.

Transverse correlations (TCs) denote the correlations between density-fluctuations along the plane parallel to a solid-liquid interface. We use molecular simulations to investigate the TCs in a model fluid near static 100, 110 and 111 faces of BCC, FCC, and SC crystals of model solids. We use the cumulant expansions of solid-liquid interfacial free energies to quantify the contribution of TCs to the interfacial free energy. We approximately decompose the above contributions into those from TCs of different ranges. Our results show that the solid-fluid attractive interaction strongly dampens the TCs, and the extent of dampening depends on the exposed face of the crystal. We also observe that the contribution from TCs near the selected surfaces differ significantly even in absence of solid-fluid attractive interaction. Overall, our results indicate a great potential for tuning the solid-liquid interfacial fluctuations by altering the crystalline nature of solid surface.