Fe-N4 graphene slab geometry optimization with K points-not converging

[Vasanthapandiyan M]

Dear colleagues,

 I have been trying to run a geometry optimization for an FeN4 slab using K points set to 2x2x1. I have experimented with different cutoff values (500 and 600), but the optimization has not converged. I utilised the Orbital Transformation (OT) method with the Gamma point, which converged successfully. However, I would like to compare the free energy differences obtained from VASP and CP2K (both with 2×2×1 k-points).

I already tried playing with different cutoffs, mixing parameters, smearing temperature values, and lowering cutoff values, but it is not working. Here, I have attached my input files. 

Any suggestions would be greatly appreciated.

Regards,

Vasanth

[Johann Pototschnig]

You can try to increase the cutoff and check its convergence for the gamma point. 

 Have you tried restarting with the converged gamma point density? 

[Vasanthapandiyan M]

Dear  Johann,

Thank you for your reply. Previously, I used the gamma point, and the calculations converged. Now, I am attempting to use K-points.