This quantity is equal to negative kT times the log of the partition function, and is defined as the amount of useful work obtainable from a thermodynamic system at constant volume and temperature.
The difference in this quantity between two systems can be determined using the Bennett acceptance ratio. By using a mean field theory approach based on the Bogoliubov inequality, this quantity can be computed for complicated systems. Subtracting the product of chemical potential and particle number from this quantity gives the grand potential. At constant temperature and volume, a minimum of this quantity corresponds to thermal equilibrium. This quantity is equal to negative kT times the log of the partition function, and is defined as the amount of useful work obtainable from a thermodynamic system at constant volume and temperature. For 10 points, name this thermodynamic potential equal to internal energy minus the product of temperature and entropy, which is named for a German physicist.
The difference in this quantity between two systems can be determined using the Bennett acceptance ratio.
Helmholtz free energy [prompt on free energy; prompt on A or F] &lt;Rombro&gt;