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

From: "M. Nicklaus" <[email-masked]>
Date: Tue, 9 Jun 1998 16:03:06 -0400 (EDT)

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       
 Fax:    (301) 496-5839                  BETHESDA, MD 20892-4255    USA 
      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
------------------------------------------------------------------------