m = 9.11*10^-31
k = 1.38*10^-23
h = 6.626*10^-34
ek = 8.627*10^-5
grat = 4
xi = 13.6
S = lambda T: (k*T/20)*(2*pi*m*k*T/h^2)^(3/2)*e^(-xi/(ek*T))
B = lambda T: 4*e^(-10.2/(ek*T))
Combo = lambda T: (B(T)/(1+B(T)))*(1/(1+S(T)))
plot(Combo,0,25000).show(xmax=25000)