[gpaw-users] Re: New GUC finite difference stencil

[Jens Jørgen Mortensen]

On Wed, 2010-02-03 at 08:27 +0100, jensj at fysik.dtu.dk wrote:
> Hi!
> 
> I have added a new type of finite difference stencil for the Laplacian. 
> For an orthorhombic cell, it is identical to the old stencil, but for a
> non-orthorhombic cell it is different from what we use in the code now. 
> My tests show that it is more efficient and accurate than the old one. The
> old O(h^2n) stencil would have up to 1+6n+12n^2 points (127 for n=3) and
> the new one has 1+2Dn points, where D is between 3 and 6 depending on
> symmetry (up to 37 points for n=3).
> 
> I would like some more testing of this new stencil - just add
> --gpaw=newgucstencil=1 on the command line.

This new stencil is now the default choice.  For an orthogonal unit cell
this doesn't change anything.

JJ