The finite difference approach consists in first establishing the P -V relationship, and then fitting it with an equation of state (EoS). P -V data is generated here by running multiple MD simulations, enforcing either various values of pressure (stress) or volume (strain), and measuring the other variable. We will talk about the finite strain difference method if the MD simulations are performed in the constant-volume (N, V, T ) ensemble by enforcing the volume V , with the resulting pressure P (V ) of the equilibrated system being measured.