[Wien] Energy origin

[John Pask]

> Slightly confused:
> 1) Integral of rho*c vanishes only if integral of rho vanishes.....?

Yes. 

> 2) What about for a not charge neutral system?

For any extended system (e.g., crystal), the (total) density must be
neutral in order for the energy to be finite. And so in such systems, the
total energy in invariant to the arbitrary constant in the potential. For
finite systems (e.g., molecules), there can be a net charge, but then the
potential is conventionally defined by the boundary condition that it
vanish at infinity.

John

> On 10/27/06, John Pask <pask1 at llnl.gov> wrote:
> >
> > > Is this true independent of whether one has a charged or a charge
> > > neutral system?
> >
> > This is true for any neutral system: integral of rho*V equals integral of
> > rho*(V+c) since integral of rho*c vanishes for any constant c.
> >
> > John
> >
> > > On 10/27/06, John Pask <pask1 at llnl.gov> wrote:
> > > >
> > > > Dear Laurence,
> > > >
> > > > Whereas the potential is unique only up to an arbitrary constant, the
> > > > total energy (per unit cell) in a periodic solid is well defined -- i.e.,
> > > > no arbitrary constant. (Shifts in the potential cancel out in the Coulomb
> > > > integrals.)
> > > >
> > > > John
> > > >
> > > > On Thu, 26 Oct 2006, Laurence Marks wrote:
> > > >
> > > > > Does anyone know of any good sources for understanding exactly what
> > > > > the energy origin is in Wien?
> > > > >
> > > >
> > > > --
> > > > --------------------------------------
> > > > John E. Pask
> > > > Physicist
> > > > Lawrence Livermore National Laboratory
> > > > University of California
> > > > P.O. Box 808, L-045
> > > > Livermore, CA 94551 USA
> > > > http://www-phys.llnl.gov/Research/Metals_Alloys/People/Pask/
> > > >
> > > > _______________________________________________
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> > > > Wien at zeus.theochem.tuwien.ac.at
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> > > >
> > >
> > >
> > >
> >
> > --
> > --------------------------------------
> > John E. Pask
> > Physicist
> > Lawrence Livermore National Laboratory
> > University of California
> > P.O. Box 808, L-045
> > Livermore, CA 94551 USA
> > phone/fax: +1 (925) 422-8392/2851
> > pask1 at llnl.gov
> >
> > _______________________________________________
> > Wien mailing list
> > Wien at zeus.theochem.tuwien.ac.at
> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> >
> 
> 
> 

-- 
--------------------------------------
John E. Pask
Physicist
Lawrence Livermore National Laboratory
University of California
P.O. Box 808, L-045
Livermore, CA 94551 USA
phone/fax: +1 (925) 422-8392/2851
pask1 at llnl.gov