GCALC(GA,GB,xB,T,I0AB,I1AB,I2AB,I3AB,I4AB,I5AB) is for calculating Gibbs energy of binary single solution system.
GCALC(GA,GB,xB,T,I0AB,I1AB,I2AB,I3AB,I4AB,I5AB) is for calculating Gibbs energy of binary single solution system.
ddGCALC(xB,T,I0AB,I1AB,I2AB,I3AB,I4AB,I5AB) is for calculating the second derivative Gibbs of binary single solution system.