From owner-chemistry -8 at 8- ccl.net Thu Jul 6 09:32:00 2017 From: "Brad Rose brose-x-live.com" To: CCL Subject: CCL: GAMESS Convergence Problem Message-Id: <-52874-170706093112-23751-Ar+5wkegaBH8qwMO+FLgoA]![server.ccl.net> X-Original-From: "Brad Rose" Date: Thu, 6 Jul 2017 09:31:11 -0400 Sent to CCL by: "Brad Rose" [brose{}live.com] Dear Sara, SCF convergence will be a problem with all the diffuse functions. It takes time and practice to learn how to tell what could be the cause, something worth your time if you plan on doing this work. The first thing I would consider is the integral cutoff values, these are ICUT and one other parameter that I don't recall offhand, I believe there should be a warning in your output about the integral cutoffs if you are running into linear dependancies (you likely are with all the diffuse functions present). To get a reasonable geometry close to the local minima I would suggest removing the diffuse functions from all but the anion and add dispersion correction (the dispersion correction is computationally cheap). Regards, Brad Rose Sent to CCL by: "Sara Mahmoud" [smahmoud%x%sci.cu.edu.eg] Sent to CCL by Sara[smahmoud|*|sci.cu.edu.eg] Dear all, I'm trying to study the adsorption of some ions on graphene flakes using GAMESS-US program. When I optimize the ion-graphene system I get this error message after several points of optimization. ***** FAILURE TO LOCATE STATIONARY POINT, SCF HAS NOT CONVERGED UPDATED HESSIAN, GEOMETRY, AND VECTORS WILL BE PUNCHED FOR RESTART **** THE GEOMETRY SEARCH IS NOT CONVERGED! **** I am using the DFT functional B3LYP with 6-31+G(d) basis set as a starting level of calculation, I'm going to justify both the functional and basis set and then include the suitable dispersion corrections in single point energy calculations. This is some of the input I used: $CONTRL MAXIT=200 ISPHER=0 $SCF DIRSCF=.T. SOSCF=.F. DIIS=.T. SHIFT=.T. DAMP=.t. $STATPT OPTTOL=0.00045 NSTEP=300 I'm a new student in the field and have no experience in GAMESS-US program. What I need to know is how can I get my jobs converged? and what are the keywords that should I use to improve the SCF convergence for this kind of interaction (ion-pi-system interaction)? Any help concerning this point will be highly appreciated. Thanks in advance for all of you. Sara