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Dawid
dawid.grabarek@pwr.edu.pl

I would like to do XMC-QDPT2 geometry optimization of the ground-state
using single-state CASSCF reference.

The issue I am encountering is that the MCSCF calculations (in course
of the geometry optimization) do not converge when high precision is
enforced even though the output looks like this:
ITER    TOTAL ENERGY          DEL(E)    LAG.ASYMM.  SQCDF  MICIT   DAMP
    ----------START APPROXIMATE SECOND ORDER MCSCF----------
  1    -439.972125989    -439.972125989  0.000560 2.088E-06  1   0.0000
  2    -439.972130903      -0.000004914  0.000203 1.353E-06  1   0.0000
  3    -439.972131634      -0.000000731  0.000060 3.849E-07  1   0.0000
  4    -439.972131722      -0.000000088  0.000021 3.551E-07  1   0.0000
  5    -439.972131755      -0.000000032  0.000009 4.861E-08  1   0.0000
  6    -439.972131760      -0.000000005  0.000008 4.466E-08  1   0.0000
  7    -439.972131763      -0.000000003  0.000004 1.206E-08  1   0.0000
  8    -439.972131764      -0.000000001  0.000002 5.590E-09  1   0.0000
  9    -439.972131764       0.000000000  0.000001 7.682E-10  1   0.0000
 10    -439.972131764       0.000000000  0.000001 1.915E-10  1   0.0000
 11    -439.972131764       0.000000000  0.000000 7.585E-11  1   0.0000
.
.
.
 95    -439.972131764       0.000000000  0.000000 1.789E-18  1   0.0000
 96    -439.972131764       0.000000000  0.000000 3.993E-18  1   0.0000
 97    -439.972131764       0.000000000  0.000000 1.440E-18  1   0.0000
 98    -439.972131764       0.000000000  0.000000 6.709E-19  1   0.0000
 99    -439.972131764       0.000000000  0.000000 5.794E-11  1   0.0000
100    -439.972131764       0.000000000  0.000011 5.792E-11  1   0.0000
EXCESSIVE NUMBER OF ITERATIONS...

Nevertheless couple of geometry searches are performed until

.
.
.

 82    -439.920263839       0.002669544  0.161276 5.195E-01  1   0.0000
      SOSCF IS SCALING ROTATION ANGLE MATRIX, SQCDF=   84.966198
      SOSCF IS SCALING ROTATION ANGLE MATRIX, DXMAX=    2.229427
 83    -439.917588524       0.002675315  0.169614 5.195E-01  1   0.0000
      SOSCF IS SCALING ROTATION ANGLE MATRIX, SQCDF=    3.359397
      SOSCF IS SCALING ROTATION ANGLE MATRIX, DXMAX=    2.229428
 84    -439.914768467       0.002820057  0.174227 5.195E-01  1   0.0000
SOSCF ENCOUNTERS A SERIOUS PROBLEM IN -SONEWT-
THE ROTATION ANGLE VECTOR HAS A HUGE NORM, SQCDF=   7.058E+03
REEXAMINE STARTING VECTORS, APPROPRIATENESS OF YOUR SCFTYP, ETC...


On the other hand, if I use default convergence criteria:

ITER    TOTAL ENERGY          DEL(E)    LAG.ASYMM.  SQCDF  MICIT   DAMP
    ----------START APPROXIMATE SECOND ORDER MCSCF----------
  1    -439.971787958    -439.971787958  0.000714 5.267E-06  1   0.0000
  2    -439.971803845      -0.000015887  0.000195 1.130E-06  1   0.0000
  3    -439.971805101      -0.000001256  0.000103 1.072E-07  1   0.0000
  4    -439.971805179      -0.000000078  0.000037 4.774E-08  1   0.0000
  5    -439.971805197      -0.000000018  0.000013 8.471E-09  1   0.0000
  6    -439.971805199      -0.000000002  0.000003 8.942E-10  1   0.0000

the MCSCF calculations converge correctly.

The active space is fine through the calculations (its size and
orbitals that create it).

So what is the possible reason for that issue? I attach input
file for calculations that do not converge correctly.

This message contains the 917 kb attachment [ input_7 ]