Mayer f-function
The Mayer f-function is an auxiliary function that often appears in the series expansion of thermodynamic quantities related to classical many-particle systems.<ref name - "mcquarrie">Donald Allan McQuarrie, Statistical Mechanics (HarperCollins, 1976), page 228 </ref>
Definition
Consider a system of classical particles interacting through a pair-wise potential
where the bold labels and denote the continuous degrees of freedom associated with the particles, e.g.,
for spherically symmetric particles and
for rigid non-spherical particles where denotes position and the orientation parametrized e.g. by Euler angles. The Mayer f-function is then defined as
where the inverse absolute temperature in units of (Temperature times the Boltzmann constant )−1 .