PRL Abstract
Abstract
The rate of change of
the entropy, S and free energy, A with respect to time
for a nonequilibrium system in a steady state
is considered. A modified Liouville
equation is derived
to account for the phase space Jacobian
arising from non-trivial
phase space compression.
With due allowance for this factor, the relations dS/dt=0
and dA/dt=0
are obtained, results that are consistent with the assumption
of a smooth,
differentiable phase space distribution function.