Entropy and Free Energy Differences by Calorimetric Thermodynamic Integration

Entropy and Free Energy Differences by Calorimetric Thermodynamic Integration 

Thus far we have discussed the absolute free energy and entropy. In many cases one is interested only in the difference of these quantities between two states, and this difference can be obtained by suitable thermodynamic integration schemes. The entropy difference of a system at temperatures Tj and is 

Equation [18] enables one to obtain the absolute entropy at if the absolute entropy at Tj is known note that for a classical system, Tj = 0 cannot be chosen because C is finite at this temperature and the integral is undefined. Calcu- 

Another integration between two densities Pj and p2 (p = N/V) at constant T leads to the corresponding difference in In Z(p) 

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