%     Input data for 2D vdW isotherm
%     Convert data from common units to SI units
%     Tc critical temperature, K
%     pc critical pressure, Pa
%     a2 cohesive parameter, J m^2
%     b2 coarea, m^2
%     A  Hamaker constant, J
%     hi interaction distance, m
%     k  Boltzmann's constant, J K^-1
      clear
      k=1.381e-23;
      Nav=6.022e23;
%     pentane on graphite*******
      A=-3.75e-20;
      hi=3.4e-10;
      Tc=469.5;
      pc=33.2    *1.01325e5;
      v=311/Nav *1.e-6;
%     **************************
      a3=(27*k^2*Tc^2)/(64*pc);
      b3=(k*Tc)/(8*pc);
      sig=(3*b3/(2*pi))^(1/3);
      C=(3*sig^3*a3)/(2*pi);
      a2=(pi*C)/(4*sig^4);
      b2=0.5*pi*sig^2;
      Tc2=(8*a2)/(27*k*b2);
      Tc3=(8*a3)/(27*k*b3);
      Data=[A k v hi a2 b2];
      save vdwdata.dat Data -ascii
