vdw and scf convergence

[Jun]

Thanks for the reply, Matt.

As far as I understand, the correction for the D2 potential is
independent of the charge density. I feel for the same geometry both
PBE and PBE+D2 converge to the same charge density (I could be wrong).
Thus, the density for a given geometry can be readily converged with
standard PBE functional, should be equally easy to converge with PBE
+D2. What the D2 vdw correction affects is only the total energy and
therefore the force. My guess is the extrapolation method somehow
doesn't take into account the vdw force.

Cheers,
Jun