[Pw_forum] Error in routine sym_rho_init_shell (4): lone vector

[Paolo Giannozzi]

On Thu, Nov 30, 2017 at 3:02 PM, Manoar Hossain <manoarphy at niser.ac.in>
wrote:

can anybody please tell me why this is happening ?
>

the code recognizes hexagonal symmetry in your data. In order to symmetrize
the charge density, the code needs to reorganize G-vectors in such a way
that only entire shells of G-vectors are present on each processor. Since
however your lattice vectors are not exactly hexagonal, the algorithm may
fail in some unfortunate cases, ending up with half a shell on one
processor, half a shell on another one. Unfortunately there is no easy
workaround, but ...

And without reducing (or changing) the lattice parameter then how one can
> get rid of this error ?
>

... if you specify your lattice vectors as

CELL_PARAMETERS
   7.1189946603   12.330460450   0.000000000
  -7.1189946603   12.330460450   0.000000000
  0.0000000       0.0000000    19.000000000

(12.330460450=7.1189946603*sqrt(3)) instead of

CELL_PARAMETERS
   7.1189946603   12.330463153   0.000000000
  -7.1189946603   12.330463153   0.000000000
   0.0000000       0.0000000    19.000000000

it works. As a rule, it is a good idea to use "exact" lattice vectors (by
specifying ibrav, or the space group) instead of user-supplied lattice
vectors whenever symmetry is important.

Paolo
-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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