Isothermal-isobaric ensemble

Variables:

• N (Number of particles)
• p (Pressure)
• T (Temperature)

The classical partition function, for a one-component atomic system in 3-dimensional space, is given by

$Q_{NpT}={\frac {1}{\Lambda ^{3}}}\int _{0}^{\infty }dVV^{N}\exp \left[-\beta pV\right]\int d(R^{3N})\exp \left[-\beta U\left(V,(R)^{3N}\right)\right]$

where

$\beta ={\frac {1}{k_{B}T}}$

References

1. D. Frenkel and B. Smit, "Understanding Molecular Simulation: From Alogrithms to Applications", Academic Press