Strongly correlating liquids

Strongly correlating liquids are defined as those for whom $R \geq 0.9$ where (Eq. 6 ^[1])

R = \frac{⟨ Δ V Δ U ⟩}{\sqrt{⟨ (Δ V)^{2} ⟩ ⟨ (Δ U)^{2} ⟩}}

where $Δ U$ represents fluctuations of the potential in the NVT ensemble and $V$ is the virial (see also Virial pressure).

Isomorphs

The liquid phase formed by the Lennard-Jones model is an example of a strongly correlating liquid^[3].