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Poor SCF convergence with re-read orbitals

Slawomir Janicki
slawomir.janicki@comcast.net


I run into SCF convergence trouble with re-read orbitals. Is there a way to increase the accuracy of punched orbitals beyond WIDE=.T. ?

In the first pass I construct the guess orbitals by:

- $GUESS GUESS=MOREAD NORB=904 KDIAG=0 EXTRA=.T. $END from a previous calculation with QZVPD on all atoms except one H with QZVP;
- adding the p diffuse functions from QZVPD to that unique H with  $EXTRAF NEXTRA(1)=0,0,0,0,0,0,0,0,0,0,0,0,0,3 $END
- declaring the basis set in $DATA

This SCF calculation converges fine in 12 iterations.

                                                                                                             NONZERO    BLOCKS
ITER EX DEM  TOTAL ENERGY      E CHANGE  DENSITY CHANGE    DIIS ERROR      VIR. SHIFT       DAMPING        INTEGRALS   SKIPPED
         * * *   INITIATING DIIS PROCEDURE   * * *
  1  0  0  -434.359184038  -434.359184038  26.000472601   0.000765616     0.000000000     1.000000000             -1 231093005
  2  1  0  -434.359184889    -0.000000851  21.033149847   0.000696271     0.000000000     1.000000000             -1 230685217
  3  2  0  -434.359185951    -0.000001062   2.264576385   0.000341393     0.000000000     1.000000000             -1 230830209
  4  3  0  -434.359186134    -0.000000183   1.741446876   0.000100257     0.000000000     1.000000000             -1 230858906
  5  4  0  -434.359186149    -0.000000015   0.110725963   0.000003935     0.000000000     1.000000000             -1 230829709
  6  5  0  -434.359186149     0.000000000   0.000703852   0.000000093     0.000000000     1.000000000             -1 230828030
  7  6  0  -434.359186149     0.000000000   0.000949385   0.000000032     0.000000000     1.000000000             -1 230828021
  8  7  0  -434.359186149     0.000000000   0.000186930   0.000000010     0.000000000     1.000000000             -1 230828001
  9  8  0  -434.359186149     0.000000000   0.000155360   0.000000006     0.000000000     1.000000000             -1 230828007
 10  9  0  -434.359186149     0.000000000   0.000225597   0.000000011     0.000000000     1.000000000             -1 230828011
 11 10  0  -434.359186149     0.000000000   0.000018039   0.000000012     0.000000000     1.000000000             -1 230828006
 12 11  0  -434.359186149     0.000000000   0.000035272   0.000000021     0.000000000     1.000000000             -1 230828006


Next, I use the orbitals from the first dat file and construct the guess orbitals for the second input file by:

- $GUESS GUESS=MOREAD NORB=907 KDIAG=0 EXTRA=.F. $END
- declaring the basis set in $DATA (the $DATA is the same as in the first input file)

The second SCF fails to converge and the energy and density oscillate wildly.

                                                                                                            NONZERO    BLOCKS
ITER EX DEM  TOTAL ENERGY      E CHANGE  DENSITY CHANGE    DIIS ERROR      VIR. SHIFT       DAMPING        INTEGRALS   SKIPPED
         * * *   INITIATING DIIS PROCEDURE   * * *
  1  0  0  -434.359184142  -434.359184142**************   0.001427558     0.000000000     1.000000000             -1 230828006
  2  1  0  -220.595295982   213.763888161   2.036093324 112.110529823     0.191843150     1.000000000             -1 219960281
  3  2  0  -561.039293414  -340.443997432   0.609648347  34.077380819     0.091843148     1.000000000             -1 219960281
  4  3  0  -586.729178088   -25.689884675   1.225957379  68.635216291     0.091843148     1.000000000             -1 219960281
  5  4  0  -506.720698955    80.008479134   0.264003476  50.804093873     0.091843148     1.000000000             -1 219960281
  6  5  0  -436.096265988    70.624432967   0.493343875  33.901854332     0.091843148     1.000000000             -1 219960281
etc.

The SCF convergence options are the same in both cases:

$SCF DIRSCF=.T. $END
$CONTRL MAXIT=100 $END
$SCF FDIFF=.F. $END
$SCF NCONV=5 $END
$SCF EXTRAP=.F. $END
$SCF SODIIS=0 DIONCE=.F. $END
$SCF SOSCF=.F. $END
$SCF DIIS=.T. ETHRSH=2500 MAXDII=10 $END
$SCF DEM=.F. $END
$SCF DAMP=.T. DMPCUT=0.0 $END
$SCF SHIFT=.T. $END
$SCF RSTRCT=.F. $END

Any idea how to fix this?

Slawomir


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