[Pw_forum] about kpoints.x

[Stefano de Gironcoli]

the two mesh should be  equivalent even if not identical

I include a simple plot of the two meshes in 2D:
kpoints.x gives a regular mesh in a triangle (the Irreducible Wedge)
pwscf.x gives also a regular mesh in an Irreducible Wedge that looks 
more complicated but is a
reflection of the previous one  w.r.t. the line from Gamma to M point 
(the center of the hexagon side)
if the triangle on  the (y<0) semiplane is shifted upward by 2/sqrt(3) 
using periodicity.

Beware that in hexagonal lattice shifted grids produce grids that do not 
have the full hexagonal symmetry.
This is why the apparent dimension of the Irreducible Wedge in the plot 
is larger than one would expect.

Try to feed the two meshes to pwscf in a sample calculation with 
otherwise identical parameters.
If the final energy, forces etc are identical the two meshes are likely 
to be equivalent.

stefano


-------------- next part --------------
A non-text attachment was scrubbed...
Name: kpoints_vs_pwscf.ps
Type: application/postscript
Size: 13545 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20060202/9bd19154/attachment.ps>