Hi,
I'm pretty sure this must have been discussed before but I cannot find it so quickly. I'm confused about the " symmetry fudging" that occurs during the SCF in NWchem 6.0.
I'm performing DFT calculations one a range of organic molecules and when I use a relatively small basis-set (e.g. 6-31G*) the SCF converges smoothly and without any warnings. When I perform a calculation on exactly the same structure with the same input-file but now only with a def2-TZVPP basis-set I suddenly get the following behavior:
convergence iter energy DeltaE RMS-Dens Diis-err time
---------------- ----- ----------------- --------- --------- --------- ------
d= 0,ls=0.0,diis 1 -1229.6972526956 -4.00D+03 1.76D-03 5.83D+00 3411.3
WARNING: error on integrated density = 0.10D-05
greater than required accuracy of 0.10D-05
!! scf_movecs_sym_adapt: 881 vectors were symmetry contaminated
Symmetry fudging
!! scf_movecs_sym_adapt: 20 vectors were symmetry contaminated
d= 0,ls=0.0,diis 2 -1230.0606455141 -3.63D-01 4.06D-04 1.08D-01 5692.6
WARNING: error on integrated density = 0.10D-05
greater than required accuracy of 0.10D-05
!! scf_movecs_sym_adapt: 1157 vectors were symmetry contaminated
Symmetry fudging
!! scf_movecs_sym_adapt: 50 vectors were symmetry contaminated
d= 0,ls=0.0,diis 3 -1230.0607072429 -6.17D-05 2.35D-04 1.05D-01 7969.4
WARNING: error on integrated density = 0.10D-05
greater than required accuracy of 0.10D-05
!! scf_movecs_sym_adapt: 986 vectors were symmetry contaminated
Symmetry fudging
!! scf_movecs_sym_adapt: 30 vectors were symmetry contaminated
d= 0,ls=0.0,diis 4 -1230.0733545208 -1.26D-02 7.70D-05 1.56D-02 10242.5
WARNING: error on integrated density = 0.10D-05
greater than required accuracy of 0.10D-05
!! scf_movecs_sym_adapt: 543 vectors were symmetry contaminated
Symmetry fudging
!! scf_movecs_sym_adapt: 6 vectors were symmetry contaminated
d= 0,ls=0.0,diis 5 -1230.0754934434 -2.14D-03 1.65D-05 7.02D-04 12520.6
WARNING: error on integrated density = 0.10D-05
greater than required accuracy of 0.10D-05
!! scf_movecs_sym_adapt: 182 vectors were symmetry contaminated
Symmetry fudging
!! scf_movecs_sym_adapt: 4 vectors were symmetry contaminated
d= 0,ls=0.0,diis 6 -1230.0755749648 -8.15D-05 5.86D-06 1.29D-04 14804.5
What is going on? If this is really a symmetry issue why does this not occur for the small basis-set calculation. I use autosym, I guess without it these issues might go away, but the SCF calculation is only the starting point for a subsequent TD-DFT calculation in which I would like to have symmetry so I can label the irreps.
Regards,
Martijn
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