My test system contains 58 atoms.I have not input any K point. Besides, the cell size is 9.38x9.38x6.7 Ang^3. Is this a small cell?
Is this molecule of bulk or slab?For molecule the cell is too small, while for bulk, I believe, you need more k-points. Somewhere around 4 processors should be optimal for such a system (if you wouldn't use more k-points).
