Adsorbed atoms moving inside the metallic slab

[thangtamfive]

Hi all,

I am running NEB computations, but the computations are not converging; I have visualized the CONTCAR files located in the 01, 02, and 03 directories of my 4-image calculation and I found that the adsorbed species instead of remaning on top of the surface have moved into the metallic slab. That is, in a 4-layer slab the adsorbed atoms not longer sit on the surface, but during the NEB calculation the adsorbed atoms move into the slab, so that after few hours of compuation the adsorbed atoms appear between the second and third layer of the metallic slab. I would like to know why this occurs and how can I prevent it.

Thanks,

[graeme]

If you post the calculation, I can take a look at it.