Subject: Re: CCL:G:DFT B3LYP/6-31+G(d,p) Convergence Problem

From: Tapas Kar <[email-masked]>
Date: Wed, 10 Jun 1998 10:40:54 -0500 (CDT)

Hi
It is sometime worth to use #P in the 1st line of com file to get more 
info on energies in each step. This gives an idea about the oscillating 
pattern of energies. Normally we use vshift if energy is oscillating. Try 
with more scf cycles, IOP(5/7=n), n is the no. of cycles you want. SCF=QC 
is another option but it takes huge CPU time.
You can restart the SCF from checkpoint file with vshift and increased 
number of scf steps. ( some cases i used 150 or even 
more number of cycles )
Tapas

 On Tue, 9 Jun 1998, M. Nicklaus wrote:

> Date: Tue, 9 Jun 1998 16:03:06 -0400 (EDT)
> From: M. Nicklaus <[email-masked]>
> To: [email-masked]
> Cc: [email-masked]
> Subject: CCL:G:DFT B3LYP/6-31+G(d,p) Convergence Problem
> 
> Dear CCL'ers,
> 
> After optimizing a structure (60 atoms, 37 non-H) at the HF/3-21G* level,
> I'm trying to calculate a DFT single point energy at the B3LYP/6-31+G(d,p)
> level, reading geometry and initial wave function from the checkpoint file.
> 
> After nearly seven days (!) of CPU time on a very fast machine, the job
> aborts without having converged, with the following end of the output file:
> 
>  Standard basis: 6-31+G(d,p) (6D, 7F)
>  There are   818 symmetry adapted basis functions of A   symmetry.
>  Crude estimate of integral set expansion from redundant integrals=1.000.
>  Integral buffers will be    131072 words long.
>  Raffenetti 2 integral format.
>  Two-electron integral symmetry is turned on.
>    818 basis functions     1345 primitive gaussians
>    132 alpha electrons      132 beta electrons
>        nuclear repulsion energy      4057.3559996761 Hartrees.
>  One-electron integrals computed using PRISM.
>  There are  17 eigenvalues of the overlap less than 1.0D-05
>  The smallest eigenvalue of the overlap matrix is  1.959D-08
>  Initial guess read from the checkpoint file:
>  dG-C8-FAAF_01-711_75.49.chk,-1
>  Warning!  Cutoffs for single-point calculations used.
>  Requested convergence on RMS density matrix=1.00D-04 within  64 cycles.
>  Requested convergence on MAX density matrix=1.00D-02.
>  Requested convergence on             energy=5.00D-05.
>  Restarting both DIIS and incremental Fock formation.
>  Restarting both DIIS and incremental Fock formation.
>  Restarting both DIIS and incremental Fock formation.
>  >>>>>>>>>> Convergence criterion not met.
>  SCF Done:  E(RB+HF-LYP) =  -34352969.2846     A.U. after   65 cycles
>              Convg  =    0.1924D-03             -V/T = *******
>              S**2   =   0.0000
>  Convergence failure -- run terminated.
>  Error termination via Lnk1e in /sbin/loader.
>  Job cpu time:  6 days 21 hours 27 minutes 49.9 seconds.
>  File lengths (MBytes):  RWF=  539 Int=    0 D2E=    0 Chk=   30 Scr=    1
> 
> 
> Any hints?  TIA
> 
> Marc
> 
> ------------------------------------------------------------------------
>  Marc C. Nicklaus                        National Institutes of Health
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>     Laboratory of Medicinal Chemistry, National Cancer Institute,  &
>   Center for Molecular Modeling, Ctr. for Information Technology, NIH
> ------------------------------------------------------------------------
> 
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-----------------
Tapas Kar, Ph. D
Asst. Scientist
Department of Chemistry
Southern Illinois University at Carbondale
Illinois 62901-4409

Fax: (618) 453 6408
Tel: (618) 453 6433