x = J/(0.69503*T)
y= J2/(0.69503*T)
MM=OP/(0.69503*T)
top1=exp(x-y)+exp(-MM)+5*exp(2*x)
top2=6*0.3751349*g*g*[(exp(x-y)+5*exp(2*x))/(T-TH)+.69503*(1-exp(-MM))/OP]
bot=1+2*exp(-MM)+3*exp(x-y)+exp(-x)+5*exp(2*x)
chiA=6*0.3751349*g*g*top1/bot/(T-TH)
chiB=top2/bot
chi=(chiA+2*chiB)/3
chi=chi*(1-ro)+ro*g*g*0.3751349*3.5/T/3+TIP