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A Problem with 2D PES scan

Yura Vishnevskiy
yuri.vishnevskiy@gmail.com


Hi All,
again I have a problem with a 2D PES scan:

 $contrl scftyp=rhf DFTTYP=B3LYP1 runtyp=rsurface
         nzvar=30 maxit=100 COORD=UNIQUE 
 $end
 $SYSTEM TIMLIM=5000000 MWORDS=100 $END
 $statpt nstep=100 nprt=-1 npun=-2 METHOD=GDIIS itbmat=100
         OPTTOL=0.0003 noreg=5
 $end
 $SCF DIRSCF=.T. $END
 $BASIS extfil=.t. gbasis=cc-pvtz $END
 $guess  guess=huckel $end
 $zmat ifdmod=2 dlc=.t. auto=.t. scan=.t.
       ifzmat(1)=3,1,2,3,4, 3,2,3,4,5
 $end
 $surf orig1=0 disp1=10 ndisp1=37 orig2=0 disp2=10 ndisp2=37 reuse=.t.
       flags=10
 $end
 $DATA
Surface-1
C1
 Cl   17.0            -0.92752000    2.09018800    0.00000000
 C     6.0             0.75671300    1.62094000    0.00000000
 O     8.0             1.03078500    0.28209400    0.00000000
 S    16.0             0.37735400   -1.24462900    0.00000000
 Cl   17.0            -1.66452600   -1.05647900    0.00000000
 O     8.0             0.75671300   -1.80106000    1.26114500
 O     8.0             0.75671300   -1.80106000   -1.26114500
 O     8.0             1.64164300    2.39695000    0.00000000
 $END

This job stops after first gradient calculation with messages:

 THE DETERMINANT OF THE G MATRIX IS 10**(   -33)
 * * * WARNING * * *
 YOUR B MATRIX HAS A SMALL DETERMINANT.
 THIS SUGGESTS YOU MAY HAVE BADLY CHOSEN COORDINATES.
          THE ROOT MEAN SQUARE ERROR IN ITERATION   3 IS   0.12338527

 THE DETERMINANT OF THE G MATRIX IS 10**(   -33)
 * * * WARNING * * *
 YOUR B MATRIX HAS A SMALL DETERMINANT.
 THIS SUGGESTS YOU MAY HAVE BADLY CHOSEN COORDINATES.
          THE ROOT MEAN SQUARE ERROR IN ITERATION   4 IS   0.12336138

 THE DETERMINANT OF THE G MATRIX IS 10**(   -33)
 * * * WARNING * * *
 YOUR B MATRIX HAS A SMALL DETERMINANT.
 THIS SUGGESTS YOU MAY HAVE BADLY CHOSEN COORDINATES.
          THE ROOT MEAN SQUARE ERROR IN ITERATION   5 IS   0.12332107

I've played with ifdmod; 2 works as described above, 0 or 1 does not work at all ("Unable to project DLC") or leads to distorted structure from the very first geometry update.

How to solve the problem? By the way, are there failsafe options for normal relaxed PES scans (without bonds breaking, using simple black box methods) so that I can do something more useful than endlessly adjusting keywords and options?

P.S. I am using Firefly 7.1.G.

[ This message was edited on Tue Dec 25 '12 at 4:43pm by the author ]


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