[CP2K:2768] Re: quadrupole moment not traceless ?

[Hanning Chen]

Axel,

  Thanks for your reply. Now, I understand why the output quadrupole moment
by CP2k is not traceless. But, it seems to me that the six quadrupole tensor
components are over complete. In fact, only five variables are needed for
uniqueness when spherical coordinate notation is used.

  Anyway, the referred page is very helpful to clarify those commonly used
definitions of quadrupole moment.

  Thanks.

Hanning

On Sun, Jun 20, 2010 at 11:54 AM, Axel <akoh... at gmail.com> wrote:

>
>
> On Jun 20, 1:04 am, Hanning Chen <chenh... at gmail.com> wrote:
> > Dear CP2k users,
> >
> >   I ran a simple SCF calculation on CO2 and found that its output
> quadrupole
> > moment (as shown below) apparently does not satisfy the requirement of
> > traceless, i.e., Q(XX)+Q(YY)+Q(ZZ)==0.
>
> >   Does CP2k have its own definition of quadrupole moment rather than the
> > standard one?
>
> there is not one but two "standard" definitions.
> a quick search on google reveals this page, for example:
>
> http://cccbdb.nist.gov/quadrupole.asp
>
> axel.
>
> >   Thanks.
> >
> > Hanning Chen
> > Ph.D.
> > Department of Chemistry
> > Northwestern University
> > Evasnton, IL 60201
> >
> > OUTPUT_FILE:
> >
> >  Reference Point [Bohr]             9.44863138      9.44863173
> > 9.44499632
> >   Charges
> >     Electronic=      -16.0000      Core=      16.0000      Total=
> > 0.0000
> >   Dipoles are based on the traditional operator.
> >   Dipole moment [Debye]
> >     X=          0.000478093061    Y=         -0.000005701601    Z=
> > 0.005608188292                   Total=            0.005628532793
> >   Quadrupole moment [Debye*Angstrom]
> >                 XX=        -18.812852208659         XY=
> > -0.089714841097         XZ=         -0.083871152755
> >                 YY=        -14.716948452691         YZ=
> > -0.002201287063         ZZ=        -14.716586168813
> >
> > INPUT_FILE:
> >
> > &FORCE_EVAL
> >   METHOD Quickstep
> >   &DFT
> >     &MGRID
> >       CUTOFF 300
> >     &END MGRID
> >     &QS
> >       EPS_DEFAULT 1.0E-12
> >     &END QS
> >     &SCF
> >       SCF_GUESS RESTART
> >       EPS_SCF 1.0E-10
> >       MAX_SCF 1000
> >       &OT
> >        MINIMIZER DIIS
> >        PRECONDITIONER FULL_KINETIC
> >       &END OT
> >     &END SCF
> >     &XC
> >       &XC_FUNCTIONAL PBE
> >       &END XC_FUNCTIONAL
> >     &END XC
> >     &POISSON
> >      POISSON_SOLVER WAVELET
> >      PERIODIC NONE
> >     &END POISSON
> >     &PRINT
> >      &MOMENTS
> >       FILENAME =dipole
> >       REFERENCE COM
> >       PERIODIC = F
> >       MAX_MOMENT 2
> >      &END MOMENTS
> >     &END PRINT
> >   &END DFT
> >   &SUBSYS
> >     &CELL
> >       ABC 10.0 10.0 10.0
> >       PERIODIC NONE
> >     &END CELL
> >     &COORD
> >   C         5.0000000838        5.0000000000        4.9999999999
> >   O         3.8098548376        4.9999999994        4.9999999994
> >   O         6.1901450757        5.0000000006        5.0000000006
> >     &END COORD
> >     &KIND C
> >       BASIS_SET DZVP-GTH-PBE
> >       POTENTIAL GTH-PBE-q4
> >     &END KIND
> >     &KIND O
> >       BASIS_SET DZVP-GTH-PBE
> >       POTENTIAL GTH-PBE-q6
> >     &END KIND
> >   &END SUBSYS
> > &END FORCE_EVAL
> > &GLOBAL
> >   PROJECT CO2
> >   RUN_TYPE ENERGY
> >   PRINT_LEVEL MEDIUM
> > &END GLOBAL
>
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