In the limit of infinitesimally small , the work corresponds to the free-energy difference between the the final and initial state. In the general case, is the irreversible work related to the free energy via Jarzynski's identity [74]:

Note that calculation of the free-energy via eq.(6.32) requires averaging of the term over many realizations of the transformation. Detailed description of the simulation protocol that employs Jarzynski's identity can be found in Ref. [78].

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