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

From: [email-masked] (Han Zuilhof)
Date: Tue, 09 Jun 1998 23:02:04 +0200

Dear Marc,

This frequently has happened to me as well, and a good work-around is
usually the following:
go from HF/3-21G* to B3LYP/3-21G* (just single point), then to
B3LYP/6-31G(d,p) (just single point again), and only finally to
B3LYP/6-31+G(d,p).

Use
geom=check & guess=read
in every step, and the same checkpoint-file.  I.e. a job like (for a
neutral singlet system):

%chk=marc
%mem=6000000
#p b3lyp/3-21G* geom=check guess=read

marc's structure

0,1

--link1--
%chk=marc
%mem=6000000
#p b3lyp/6-31G(d,p) geom=check guess=read

marc's structure

0,1

--link1--
%chk=marc
%mem=6000000
#p b3lyp/6-31+G(d,p) geom=check guess=read scf=tight

marc's structure

0,1

An approach like this worked in nearly all of my b3lyp/6-31+G(d,p) jobs!

Good luck,
Han

-------------------------

At 4:03 PM 6/9/98, M. Nicklaus wrote:
>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
> E-mail: [email-masked]               Bldg 37, Rm 5B29
> Phone:  (301) 402-3111                  37 Convent Dr, MSC 4255
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>      http://rex.nci.nih.gov/RESEARCH/basic/medchem/mcnbio.htm
>    Laboratory of Medicinal Chemistry, National Cancer Institute,  &
>  Center for Molecular Modeling, Ctr. for Information Technology, NIH
>------------------------------------------------------------------------
>
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______________________________________________________________________
Han Zuilhof                         |  E-mail:  [email-masked]
Laboratory of Organic Chemistry     |  FAX   :  31-317-484914
Department of Biomolecular Sciences |  phone :  31-317-482367
Wageningen Agricultural University  |
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