  The nonequilibrium free energy theorems show how distributions of work along
nonequilibrium paths are related to free energy differences between the
equilibrium states at the end points of these paths. In this paper we develop a
natural way of barostatting a system and give the first deterministic
derivation of the Crooks and Jarzynski relations for these isothermal isobaric
systems. We illustrate these relations by applying them to molecular dynamics
simulations of a model polymer undergoing stretching.
