Invariance of free energy against a shift of the dividing surface of arbitrary geometry

摘要

This paper demonstrates that within the context of the generalized theory of capillarity, the free energy remains invariant against an arbitrary shift of the dividing surface for a general surface geometry. The Gibbs adsorption equation is used to illustrate the importance of being able to shift the dividing surface. The mathematical proof makes use of an equation describing the change of free energy for a shift of the dividing surface, derived in an independent development of a hydrostatic approach to capillarity.