periodic boundary conditions

[Ondrej Certik]

Hi,

can we do periodic boundary conditions in hermes2d and 3d?

It would be useful for MHD, so that I can compare directly with a
finite volumes solver, which uses them.

But more importantly, it would allow us to solve the Schroedinger
equation in a lattice, which would be excellent for comparing with
other people who do that, and to solve band structures of crystals,
see here if you are not familiar with band structures:

http://en.wikipedia.org/wiki/Electronic_band_structure

Ondrej

[Pavel Solin]

Ondrej,
  we do not do that yet, but it can be done. Periodic BC cannot
be used with an arbitrary domain -- the domain itself has to be
periodic. The periodicity can occur in any given direction, which
is not necessarily the x-axis or the y-axis. If we decide to do this,
we should do it right.

Pavel

--
Pavel Solin
University of Nevada, Reno
http://hpfem.math.unr.edu/people/pavel/
Hermes project: http://hpfem.org/
FEMhub project: http://femhub.org/

[Ondrej Certik]

On Mon, Aug 17, 2009 at 12:17 AM, Pavel Solin<so...@unr.edu> wrote:
> Ondrej,
>   we do not do that yet, but it can be done. Periodic BC cannot
> be used with an arbitrary domain -- the domain itself has to be
> periodic. The periodicity can occur in any given direction, which

Thanks for the info. Yes, the domain is periodic in both of my applications.

> is not necessarily the x-axis or the y-axis. If we decide to do this,
> we should do it right.

Let's make a plan at the scipy conference in 3 days. I think we should
implement that eventually, but I am not sure if we should do that now,
or rather later on.

Ondrej

[Pavel Solin]

I believe that our first priority should be to finish DFT.
The periodic BC are a technical detail, there is
nothing deep in there.

Pavel

[Ondrej Certik]

On Mon, Aug 17, 2009 at 12:26 AM, Pavel Solin<so...@unr.edu> wrote:
> I believe that our first priority should be to finish DFT.
> The periodic BC are a technical detail, there is
> nothing deep in there.

I think so too. Once we have the DFT (both 2d and 3d), the door into
the electronic structure world will suddenly open for us and we'll
then have several options to go forward (e.g. pseudopotentials vs. all
electron calculations, periodic vs. nonperiodic, we can play with the
adaptivity, and so on).

Ondrej