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# Gaussian Density Matrix Is Not Changing But Iis Error

Date: Tue, 28 Nov 2006 18:02:00 +0100 Sent to CCL by: Eric Breynaert [eric.breynaert_._biw.kuleuven.be] Thanks for the suggestions. I'm giving an overview below. 1/ - SCF=qc will probably solve the problem, albeit at a cost - Change the SCF converger to either SD, Quadratic or Fermi 2/ - lower the symmetry of optimize with and optimize with the "nosymm" keyword I solved the problem using a variation on the first suggestion. Normally the scf took less than 80 cycles to converge. So i used scf=(Maxconventionalcycles=100,xqc) which resulted in a good compromise between using scf=qc and optimisation speed. In the case of the DIIS error the scf always took more than 100 cycles before the error, so by adding scf=(Maxconventionalcycles=100,xqc) the scf switched to qc after 100 cycles in the standard DIIS mode. Regards, Eric u wrote: Sent to CCL by: "Eric Breynaert" [Eric.breynaert]=[biw.kuleuven.be] Hello all, I'm trying to optimize a transition metal structure using DFT ub3lyp LANL2DZ basisset for the metal center , 6-31G(d) for all other elements o.a. O, H, C, S, .... In most cases the optimisation succeeds. But sometimes g03 generates the following error after about 20 to 80 steps in the optimisation. Density matrix is not changing but DIIS error= 2.02D-05 CofLast= 3.35D-01. The SCF is confused. I've already btried different approaches to get arround this but nothing has succeeded. For example, recalculating force constants on the geometry obtained 1 or 2 steps before the error. Forcing g03 to make a new guess at every step of the optimisation using guess=(mix,always). Has anyone encountered such a problem before, or do you know a solution to it ? Thanks, Kind Regards, Eric-- Eric Breynaert Labo voor Colloïdchemie Kasteelpark Arenberg 23 B-3001 Leuven Tel: +3216321457 Fax: +3216321998 Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

this problem in many body files I am getting the error in Gaussian 03 .The error is " The SCF is confused."? The error is Density matrix is not changing but DIIS error= 1.35D-02 CofLast= 3.25D-02. The SCF is confused. Error termination via Lnk1e in C:\G03W\l502.exe at Sat Nov 08 18:21:40 2014. Job cpu time: 0 days 0 hours 43 minutes 7.0 seconds. File lengths (MBytes): RWF= 41 Int= 0 D2E= 0 Chk= 2 Scr= 1 My input file path is %mem=512mb # pbepbe/6-311+g(d) massage scf=(qc,maxcycle=4096)test Please help me how to overcome this  thank you. Topics Computational Physics × 383 Questions 44,537 Followers Follow Gaussian (Software) × 767 http://www.ccl.net/chemistry/resources/messages/2006/11/28.011-dir/ Questions 305 Followers Follow Nov 12, 2014 Share Facebook Twitter LinkedIn Google+ 0 / 0 All Answers (4) Hamad R. Jappor · University of Babylon this error appear because pbepbe required fitting set in some cases  to overcome this error use fitting set SVP or TZVP or QZV or any other fitting set, you can find another fitting sets in guessveiw if you active this option if you chose pbepbe after the basis https://www.researchgate.net/post/Can_any_body_help_me_how_to_overcome_this_problem_in_many_body_files_I_am_getting_the_error_in_Gaussian_03_The_error_is_The_SCF_is_confused set windows Nov 13, 2014 Venkatesan Ragavendran · Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya University HI, I think that your method does not suits your molecule. May be you can try the same with different combination sets. Nov 15, 2014 Ravinder Suresh Konda · The Institute of Science, Mumbai thank you venkatesan Ragavendran sir but all files are with  same method but some files are not running Nov 15, 2014 Kapil Dhaka · Technion - Israel Institute of Technology Dear Ravinder,  Possible solutions of convergence failure in gaussian 1)  SCF=qc will probably solve the problem, albeit at a cost. Change the SCF converger to either SD, Quadratic or Fermi 2)  lower the symmetry of optimize with and optimize with the "nosymm" keyword A variation on the first suggestion. Normally the scf took less than 80 cycles to converge. So i used scf=(Maxconventionalcycles=100,xqc) which resulted in a good compromise between using scf=qc and optimisation speed. In the case of the DIIS error the scf always took more than 100 cycles before the error, so by adding scf=(Maxconventionalcycles=100,xqc) the scf switched to qc after 100 cycles in the standard DIIS mode. I think it will work.  Best wishes  Kapil Dhaka Nov 16, 2014 Can you help by adding an answer? Add your answer Question followers (6) Kapil Dhaka Technion - Israel Institute of Tec

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