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Lattice dynamics model calculation of Kapitza conductance at solid-fluid interfaces

Existing theoretical models of the interfacial thermal conductance, i.e., Kapitza conductance, of insulating solid-fluid interfaces only consider bulk properties, e.g., acoustic mismatch model and diffuse mismatch model. In this work, we propose a classical lattice dynamical model calculation of the Kapitza conductance, thereby incorporating interfacial structural details. In our model, we assume that heat is mostly carried by phonons in the solid, and that sound waves carry diffusive heat from the interface into the bulk of the liquid, where both longitudinal and transverse sound waves are considered. Sound wave dispersion is calculated from the fluid pair distribution function, evaluated using approximate integral equation theories (i.e., Percus-Yevick, Hypernetted-chain approximation). The Kapitza conductance of the solid-fluid interface is obtained from the phonon transmission coefficient at the interface. We determine the interfacial phonon transmission coefficient by solving the coupled equations of motion for the interfacial solid and fluid atoms. As an illustrative example, we derive the Kapitza conductance of solid argon-fluid neon interface, with pair-wise Lennard-Jones interactions.