화학공학소재연구정보센터
Journal of Chemical Physics, Vol.114, No.14, 6007-6013, 2001
Positive definiteness of entropy production in the nonlinear Robertson formalism
The Robertson formalism, which derives from the Liouville equation via a projection operator a kinetic equation obeyed exactly by the information-theoretic phase space distribution, is used to calculate (S) over dot, the time-derivative of the Jaynesian model of entropy. The Robertson kinetic equation involves an operator (T) over cap for which Robertson gives an expression whose terms must be regrouped to consider times t>>tau, with tau the relaxation time of a variable eta (t) having properties typical of fast variables of extended thermodynamics. When driving forces are applied, causing the system to approach a steady state with constant eta, one can show that (S) over dot greater than or equal to0 as t --> infinity for experimentally-accessible states. In practice, this holds so long as t>>tau, i.e., for the time scale of most measurements in simple fluids. It is also found that (S) over dot = S(0)t >0 as t -->0 for an arbitrary nonequilibrium initial state.