# Isobaric ensemble

In such an ensemble we have the reservoir with fixed temperature and pressure. Under these assumptions, the probability that the system has a certain value of energy ${\displaystyle E}$ and volume ${\displaystyle V}$ is:

${\displaystyle P(E,V)={\frac {1}{Z_{P}}}g(E,V)e^{-\beta (E+pV)}}$

Moreover, in such an ensemble we have:

${\displaystyle G=-kT\log Z_{P}}$