# Widom test-particle method

Revision as of 17:43, 29 January 2008 by Carl McBride (talk | contribs)

The excess chemical potential is given by

where is the Boltzmann constant, *T* is the temperature, *N* is the number of particles within the system and is the interaction potential energy between the randomly placed test particle and the *N* particles that the system is comprised of.

## References

- B. Widom "Some Topics in the Theory of Fluids", Journal of Chemical Physics
**39**pp. 2808-2812 (1963) - B. Widom "Potential-distribution theory and the statistical mechanics of fluids", Journal of Physical Chemistry
**86**pp. 869 - 872 (1982) - David S. Corti "Alternative derivation of Widom's test particle insertion method using the small system grand canonical ensemble", Molecular Physics
**93**pp. 417-420 (1998)