Predictive Soave-Redlich-Kwong (PSRK)

Generic cubic equation of state (explicitly arranged for pressure):

<math> P = { { R \; T } \over { V - b } } - { { a(T) } \over { ( V + \epsilon * b ) * ( V + \sigma * b ) } } </math>

Parameters for Soave-Redlich-Kwong equation are:

<math> \epsilon = 0</math> and <math> \sigma = 1</math>