## Fugacity

### Function

 definiendum $z(\beta,\mu):=\mathrm e^{\beta\cdot\mu}$

#### Discussion

Not to be confused with the fugacity coeffient $\phi$, which is a pressure value used to model abbaviations from the ideal gas model pressures. The unitless normalized fugacity coeffient is called thermodynamic activity $a$, which is closer to $z$. The so called activity $a_B$ on the other hand is the non-ideal analogue of a concentration.