2012-05-16
9:30 at HCI J 574

Local equilibrium of the Gibbs interface in two-phase systems

Thierry Savin

Polymer Physics, Department of Materials, ETH Zurich

The classical approach to equilibrium interfacial thermodynamics in phase coexistence describes the interface as a separate two dimensional thermodynamic system characterized by excess densities. Gibbs' original formulation relies on the uniformity of intensive variables throughout the system. Therefore, it cannot be directly applied to nonequilibrium situations such as evaporation/condensation processes or heterogeneous catalysis, where jumps in temperature and chemical potential across the interface can occur.

We present a conceptually clear formulation of local equilibrium for interfaces. In particular, we gain new insights by formulating, in terms of gauge transformations, the ambiguity in locating the interface. This notably allows us to generalize the Clapeyron relationships to nonequilibrium situations. We support our theoretical predictions by performing stringent tests with nonequilibrium molecular dynamics simulations.