Green kubo thermal conductivity

Dear All,

I am calculating thermal conductivity of gas based nanofluid using Green Kubo. The problem I am facing is even for larger sampling parameters i.e. p = 40000 and s =1 or 2 my HCACF is not converging . I have used the time step of 1 fs. Also, in lammps the green kubo code does not subtract enthalpy term from the convective term. How do I subtract that enthalpy term to get the correct thermal conductivity value? Any kind of help os highly appreciable Sir.