The Benedict–Webb–Rubin–Starling equation of state is a modified BWR equation of state and can be written as p = ρ ρ R T + ( B 0 R T − − A 0 − − C 0 T 2 + D 0 T 3 − − E 0 T 4 ) ρ ρ 2 + ( b R T − − a − − d T + c T 2 ) ρ ρ 3 + α α ( a + d T ) ρ ρ 6