[Pw_forum] problem of relaxation

[Paolo Giannozzi]

Hi

>  H    0.5000000      0.2500000      0.936176 0 0 1
>  Cu   0.2500000      0.2500000      0.707107 0 0 0
>  Cu   0.2500000      0.7500000      0.707107 0 0 0
>  Cu   0.7500000      0.2500000      0.707107 0 0 0
>  Cu   0.7500000      0.7500000      0.707107 0 0 0
>  Cu   0.0000000      0.0000000      0.353553 0 0 0
>  Cu   0.5000000      0.0000000      0.353553 0 0 0
>  Cu   0.0000000      0.5000000      0.353553 0 0 0
>  Cu   0.5000000      0.5000000      0.353553 0 0 0
>  Cu   0.2500000      0.2500000      0.000000 0 0 0
>  Cu   0.2500000      0.7500000      0.000000 0 0 0
>  Cu   0.7500000      0.2500000      0.000000 0 0 0
>  Cu   0.7500000      0.7500000      0.000000 0 0 0

this means that H is allowed to move along z only, and 
that all other atoms are not allowed to move. I am not 
sure that this case will work. The implementation of 
constraints is somewhat shaky. 

In general: in the manual there is some explanation 
of why things can go bad during structural optimization.
Those reasons apply to the "unexpected error" case
as well.

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050509412
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