A short question on SCF calculations with a point charge

[evgeniy]

Dear TM Aficionados,

I am interested in scf calculations with a point charge (using option $point_charges).
I wonder if one can do such calculations with TM keeping the initial symmetry
of the molecule; it is assumed that the charge does not  break the initial syymetry of the molecule?

Many thanks!

Best regards,
Evgeniy

[christof.haettig]

Yes. The charges must not break the symmetry... or they will be symmetrized by TM.

Regards,
Christof

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[evgeniy]

Dear Christof,

Many thanks for your response. I posed my question because I encountered a problem when
running dscf (TM 6.5) with a point charge, and keeping the symmetry. The problem is the SCF converges to a wrong
solution with a very low energy, which is apperently an artifact or might be a bug. However,
when I ran the same job in C1 (no symmetry at all) everything went fine. To check this behavior I ran
H2O with a charge 0.01 in the origin (Just in case, below is the input). With symmetry I got the energy
-159.952466 and without symmetry I got -76.039612, which seems to be coorect as without charge
the energy is -76.065196.

So, I wonder what can be wrong? Can it be a bug?

Best regards,
Evgeniy


$operating system unix
$title
Check water with charges HF/cc-pVQZ
$coord
    0.00000000000000      0.00000000000000     -0.73683995254846      o
   -1.41466847160833      0.00000000000000      0.36841981291867      h
    1.41466847160833      0.00000000000000      0.36841981291867      h
$symmetry c2v
$atoms
o  1                                                                           \
   basis =o cc-pVQZ
h  2-3                                                                         \
   basis =h cc-pVQZ
$basis    file=basis
$rundimensions
   dim(fock,dens)=10290
   natoms=3
   nshell=35
   nbf(CAO)=140
   nbf(AO)=115
   dim(trafo[SAO<-->AO/CAO])=281
   rhfshells=1
$scfmo   file=mos
$scfiterlimit       30
$scfconv        7
$thize     0.10000000E-04
$thime        5
$scfdamp   start=0.300  step=0.050  min=0.100
$scfdump
$scfintunit
 unit=30       size=0        file=twoint
$scfdiis
$scforbitalshift  automatic=.1
$drvopt
   cartesian  on
   basis      off
   global     off
   hessian    on
   dipole     on
   nuclear polarizability
$interconversion  off
   qconv=1.d-7
   maxiter=25
$optimize
   internal   off
   cartesian  on
   global     off
   basis      off   logarithm
$coordinateupdate
   dqmax=0.3
   interpolate  on
   statistics    5
$forceupdate
   ahlrichs numgeo=0  mingeo=3 maxgeo=4 modus=<g|dq> dynamic fail=0.3
   threig=0.005  reseig=0.005  thrbig=3.0  scale=1.00  damping=0.0
$forceinit on
   diag=default
$energy    file=energy
$grad    file=gradient
$forceapprox    file=forceapprox
$point_charges
0.0 0.0 0.0 0.01
$closed shells
 a1      1-3                                    ( 2 )
 b1      1                                      ( 2 )
 b2      1                                      ( 2 )
$end

[christof.haettig]

It looks like a bug. Please contact the helpdesk turbomole@cosmologic.de.
We became just this week aware that there is a bug when pointcharges are used together with symmetry .

Christof