[Pw_forum] error information

[Paolo Giannozzi]

On Wednesday 27 August 2003 17:15, Eyvaz Isaev wrote:
> Dear Zhenyu,
>
> The error was discussed early in the forum [...]
> You can slightly change your input file (Ecut and
> Ecutrho) and the error should disappear.

unfortunately it is not that simple. This is an error
that should never happen. If it does, something 
is seriously wrong. This is what the manual says:
   - serious error in data, such as bad atomic positions or bad
      crystal structure/supercell;
   - a bad PP (for instance, with a ghost);
   - IBM SP3: under some circumstances (typically a large number
       of k-points) we get an error in cdiaghg that is reproducible
       but disappears if we change anything in the calculation.
       We don't know what happens and why. Try to use
       conjugate-gradient diagonalization (diagonalization='cg').
    - HP-Compaq alphas with cxml libraries: try to use
       compiled Blas/Lapack (or better, Atlas) instead of those
       contained in cxml (just load them before cxml).
It might also be a consequence of the following case:
   - Structural optimization goes wild after first or second step.
      The algorithm used in structural optimization is not very robust.
      If you start too far away from minimum, it may lead to badly
      wrong atomic positions. Restart from a better starting point.
Paolo
-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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