UT theoretical chemistry code forum

How does the FMAGFLAG changes the convergent forces criterion?

It is really necessary to set FMAGFLAG tag in INCAR for a ClNEB run?

How to set this tag? FMAGFLAG = .TRUE.?

For a standard vtstcode included vasp, the forces in the OUTCAR may be read like below:

NEB: the previous image is higher in energy: F
NEB: the next image is higher in energy : F
NEB: image is at an extrema
NEB: diff energy (min, max): 762.479528 762.479528
NEB: forces: par spring, perp REAL, dneb 304.963231 0.478778 0.000000
NEB: distance to prev, next image, angle between 69.443272 8.450626 91.535402
NEB: projections on to tangent (spring, REAL) -304.963231 -0.322032

FORCES: max atom, RMS 0.184192 0.052673
FORCE total and by dimension 0.577003 0.171505

For a ClNEB run without FMAGFLAG set in INCAR, the nebef.pl searchs for "FORCES: max atom" and the value 0.184192 to compare with the force criterion EDIFFG(< 0).

If FMAGFLAG set in INCAR, which kind of forces will be chosen to compare with the convergent force criterion?

When the FMAGFLAG is set, the the convergence criterion is based upon the total RMS force for all atoms instead of the max RMS force for any atom.