Dear Abraham, first of all thank you very much for your reply, it was very usefull and I was able to make my small test calculations converge. But now I moved to larger systems and I get very anoying runtime errors that make my calculations crash. The runtime errors I get are the following:
forrtl: severe (174): SIGSEGV, segmentation fault occurred Image PC Routine Line Source mca_pml_ob1.so 00002B0077DBE1C8 Unknown Unknown Unknown mca_pml_ob1.so 00002B0077DBE493 Unknown Unknown Unknown mca_btl_sm.so 00002B0078C462AC Unknown Unknown Unknown libopen-pal.so.0 00002B007319D427 Unknown Unknown Unknown libmpi.so.0 00002B0072C8B596 Unknown Unknown Unknown libmpi.so.0 00002B0072CBA83E Unknown Unknown Unknown libmpi_f77.so.0 00002B0072A4744F Unknown Unknown Unknown siesta_mod2 00000000004BA2B0 redistribxy_ 657 fft3d.F siesta_mod2 00000000004ABAE3 fft_ 196 fft3d.F siesta_mod2 00000000005D89DE poison_ 109 poison.F siesta_mod2 00000000004A1AD2 dhscf_ 535 dhscf.F siesta_mod2 00000000005FEB57 m_setup_hamiltoni 214 setup_hamiltonian.F siesta_mod2 000000000063D68A m_siesta_forces_m 78 siesta_forces.F siesta_mod2 000000000063D86C MAIN__ 23 siesta.F siesta_mod2 000000000044CEEC Unknown Unknown Unknown libc.so.6 00000030FFE1D994 Unknown Unknown Unknown siesta_mod2 000000000044CDF9 Unknown Unknown Unknown [compute-2-18.local:989144] [[59087,0],1]-[[59087,1],12] mca_oob_tcp_msg_recv: readv failed: Connection reset by peer (104) -------------------------------------------------------------------------- mpiexec has exited due to process rank 12 with PID 989149 on node compute-2-18 exiting without calling "finalize". This may have caused other processes in the application to be terminated by signals sent by mpiexec (as reported here). -------------------------------------------------------------------------- I already encoutered segmentation faults and I got through them by increasing the number of cores, so that is what I am going to do now as well... but this isn't something I can keep doing since now I am dealing with only 72 atoms at a time but I will have to simulate much bigger systems. I hope I am not asking to much but have you ever encoutered such erros? Have you any clue? It looks like if the problem is in the fft routine so I will start increasing and decreasing the MeshCutoff that now is set to 150 Ry for a 20x37x20 Angstrom supercell, what do you think? Thank you very mch for any help you can give me. With best regards, Luigi. 2013/5/30 Abraham Hmiel <[email protected]> > 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 > >
