Quick question on selective dynamics

[richard_kang]

Hello,

I think I found a related question which was uploaded long time ago relevant to this but needed a further clarification.
I am using selective dynamics tag for ionic relaxation, but I am specifically fixing only the Z-coordinate of a certain atom. (i.e. T T F)
I'm doing a quite coarse optimization, so using EDIFFG=-0.05 for the convergence criterion.

I was wondering about how VASP treats the force on this atom.
So for example for a finished electronic step which gives this on the above atom:

25166 POSITION TOTAL-FORCE (eV/Angst)
25167 -----------------------------------------------------------------------------------
25168 -0.00039 0.00029 0.00000 0.002144 0.001395 0.036577


Because I specified, TTF, would projection of the force to the xy-plane still be considered for convergence criterion?
(i.e. evaluate if 0.002144^2 + 0.001395^2 = 0.0367 is smaller than 0.05)
Or would the force be just ignored for convergence criterion whatsoever per the F?

Thank you very much!
Richard

[ferenc_karsai]

In the code all atoms contribute to the force threshold, but the forces on the atoms with .FALSE. are set to zero. This is way they effectively don't contribute to the threshold.

[richard_kang]

Ah okay, thanks!
But since the atom is labeled TTF, it will still be able to move around in the direction of first two lattice vectors right?
Thanks for the reply.

[ferenc_karsai]

Yes of course, the forces will fully act on the first two dimensions.