CCL:G: SCF is confused?

 Sent to CCL by: "Antonio G De Crisci" [antonio.decrisci[-]utoronto.ca]
 I also had this problem (for a UHF calculation). Using the quadratic SCF (as
 stated below: scf=qc or scf=xqc) and taking of symmetry by using the NoSymm
 keyword solved the issue for me.
 Hope that helps.
 Antonio De Crisci,
 Ph.D. Candidate
 Department of Chemistry
 University of Toronto
 > "McGaughey, Georgia B. georgia_mcgaughey*|*merck.com"  wrote:
 >
 > Sent to CCL by: "McGaughey, Georgia B."
 [georgia_mcgaughey{}merck.com]
 > Sarah,
 >
 > Have you tried any other key words?  For calculating dimer interactions
 > using MP2/aug-cc-pvdz, I typically use the Counterpoise=3D2 keyword (in
 > Gaussian) along w/ SCF=3D(qc,tight,maxcycle=3D512).  I too had "SCF is
 > confused" in my output on occasion prior to adding in the SCF syntax.
 >
 > -Georgia=20
 >
 > -----Original Message-----
 > > From: owner-chemistry!=!ccl.net [mailto:owner-chemistry!=!ccl.net]=20
 > Sent: Monday, June 30, 2008 8:39 AM
 > To: McGaughey, Georgia B.
 > Subject: CCL:G: SCF is confused?
 >
 >
 > Sent to CCL by: "Sarah R Whittleton" [SWhittleton|dal.ca]
 > Hi CCL,
 >
 > I am trying to run a BSSE single-point calculation (counterpoise) using
 > MP2 on an organotin compound.  The tin atom is described using the
 > Stuttgart ECP and an augmented, triple-zeta basis set.  After running
 > for 11 hours the calculation dies uncompleted and the output (copied
 > below) says that Density matrix is not changing but DIIS error and the
 > SCF is confused.  I have run similar calculations with the same method
 > on different organotin compounds and this is the only one giving me
 > trouble.  I want to keep the method (MP2) and basis set consistent
 > between compounds  is there anything I can do to make resolve this
 > problem and allow the calculations to complete normally?  I have also
 > included the first lines of the input file for this calculation.
 >
 > I thank you all in advance for any suggestions,
 > Sarah Whittleton
 > =09
 > ********************************
 > Ph.D. Candidate
 > Department of Chemistry
 > Dalhousie University
 > Halifax, NS  B3H 4J3
 >
 >
 > THE END OF THE OUTPUT FILE:
 > The electronic state of the initial guess is 2-A.
 >  <S**2> of initial guess=3D 0.7500
 >  Requested convergence on RMS density matrix=3D1.00D-08 within 128 cycles.
 >  Requested convergence on MAX density matrix=3D1.00D-06.
 >  Requested convergence on             energy=3D1.00D-06.
 >  No special actions if energy rises.
 >  Restarting incremental Fock formation.
 >  Density matrix is not changing but DIIS error=3D 1.23D-06
 > CofLast=3D-1.58D-02.
 >  The SCF is confused.
 >  Error termination via Lnk1e in /usr/local/gaussian/g03/l502.exe at Tue
 > Jun 24 22:30:03 2008.
 >  Job cpu time:  0 days 11 hours  8 minutes 18.9 seconds.
 >  File lengths (MBytes):  RWF=3D  65118 Int=3D      0 D2E=3D      0 Chk=3D
 =
 >     8
 > Scr=3D      1
 >
 >
 > THE INPUT FILE:
 > %mem=3D2GB
 > %nprocs=3D3
 > %chk=3DMP2-test.chk
 > # MP2/GenECP Pseudo=3DRead counterpoise=3D2 maxdisk=3D200GB
 >
 >
 >
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