[Pw_forum] K_POINTS, tpiba or crystal

[Gabriele Sclauzero]

Dear Paul,

   I add just a small note that maybe will help you further in checking k-points 
coordinates. If you put
   verbosity='high'
in the control namelist, the program will show you on output the set of k-points 
coordinates used for that calculation expressed in both 'tpiba' and 'crystal' reference 
frames, so that you can better check the difference (if any, depending on the crystal itself).

GS

Paul M. Grant wrote:
> Followup on K_POINTS: tpiba vs crystal...
> 
> As usual, Paolo is right...for sc lattices (ibrav=1), tpiba or crystal give
> equal nscf outputs.
> 
> But, for fcc lattices (ibrav=2), it apparently does!  See below comparing
> nscf k-vector outputs for tpiba and crystal, and crystal is very different
> (and weird...for me anyway).  BTW, whether tpiba, etc., should be enclosed
> in curly braces or parentheses or nothing on the K_POINTS card is confusing.
> PW_INPUT shows braces, but parenthese work too, and probably no delimiters
> as well.
> 
> My agenda here is to generate k-points grids amenable to applications that
> cannot use simply MP weighted points in the irreducible BZ, such as
> epsilon.x.  I'm finding the algorithm used by Eyvaz Isaev for Fermi Surface
> plotting which uniformly populate and span the fundamental reciprocal
> lattice cell works quite well...if inputted with tpiba or "blank," not
> crystal.
> 
> 
> TPIBA VS CRYSTAL COMPARISON RE FCC FOLLOWS
> =================================================== 

-- 


o ------------------------------------------------ o
| Gabriele Sclauzero, PhD Student                  |
| c/o:   SISSA & CNR-INFM Democritos,              |
|        via Beirut 2-4, 34014 Trieste (Italy)     |
| email: sclauzer at sissa.it                         |
| phone: +39 040 3787 511                          |
| skype: gurlonotturno                             |
o ------------------------------------------------ o