Huge drift forces

[MCV]

Hi,

I have problems converging the geometry optimization of a surface model.

I get huge drift forces (>13 eV/A) although:
- all atomic forces are below the convergence thresold (<0.02 eV/A)
- all forces cancel out by symmetry (I also added them up in a spreadsheet and the result for each xyz coordinate is 0)

I tried every trick in the vasp handbook with no result in the calculation whatsoever:
- I increased NGX,NGY,NGZ values to avoid wrap-around errors
- I set up the ENCUT above the minium value in the POTCAR file (I always do)
- I increased the number of K points

I'm quite puzzled about this. What else could I do ?

Thanks a lot for your help.

Yours,
MCV

[admin]

the drift in forces usually indicates that the basis size should be increased.
please set ENCUT to at least 1.3 * max (ENMAX) of the POTCARS