[Pw_forum] error information

[Paolo Giannozzi]

On Thursday 28 August 2003 14:32, Zhenyu Li wrote:

> [...] after increasing the values of ecut and ecutrho, I get another error:
> [...] from linmin : error #         2
>       unexpected error

>How to solve this problem now?

see my preceding message, towards the end:

  - 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.

and also (from the next version of the manual):

  - Structural optimization stops in linmin with "unexpected error".
     The line minimization algorithm (linmin) looks for a minimum
     -- using atomic positions and forces at  the current and preceding
     step, and 3rd- or 2nd-degree polynomial interpolation -- along a
     given direction (determined by the BFGS algorithm). If this minimum
     turns out to be where it shouldn't be (for instance, on the wrong
     side with respect to forces), the code stops with "unexpected error".

     In practice, this means that there is an inconsistency between
     forces and energies 

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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