Hi Luigi, A few suggestions:
1) Your MaxCGsteps and MaxSCFIterations are both very large, convergence in many problems can be adequately approached by using a small number of CG updates, like 10-50 to perform a stepwise convergence, changing mixing parameters slightly between runs, observing how the forces change between CG steps and using UseSaveData = .true. to use saved DM's, XV's and so on. MaxSCFIterations could be around 100-250, much more than that and you're wasting your time, might I add. 2) Try using more Pulay convergence parameters. This will probably get you to convergence if you choose them right. You will have to modify them until you attain something that works. For starters, try: DM.NumberPulay 5 DM.MixingWeight 0.002 DM.NumberKick 12 DM.KickMixingWeight 0.0766 I've found that oftentimes the Pulay "kick" will knock your SCF cycle into a convergence basin, especially with charged systems or hard pseudopotentials. Look in the manual to see how these are defined. 3) I'm not sure why SimulateDoping would help you, it seems unphysical to me in a molecule rather than a solid. Your meshcutoff also seems low, but it won't help your convergence problem. Look into converging that value once you can close your SCF loop. 4) 30x30x30A cell is a big box for a small molecule, perhaps there may be a benefit to using a smaller cell, since a Madelung correction term is applied for molecules? If you go to a 20x20x20 cell does the convergence issue get worse? That's all I can think of for now, definitely look into the Pulay convergence acceleration though. Warm regards, *Abraham Hmiel* Katherine Belz Groves Fellow in Nanoscience Xue Group, College of Nanoscale Science and Engineering at SUNY Albany http://abehmiel.net/about
