On the geometric structure of thermodynamics

In this paper we consider symmetry transformations of the generalized entropy function that preserve the Gibbs one-form (Gibbs relation). We show that this symmetry consideration naturally leads to the geometric structure of thermodynamics in terms of contact geometry. We also construct an example based on the van der Waals' fluid to illustrate the method discussed in the paper. (C) 1999 American Institute of Physics. [S0022-2488(99)03102-3].