[CP2K-user] Structure error when calculating PDOS

[Ref]

Fabian, thanks for the clarification!

среда, 6 мая 2020 г., 16:21:09 UTC+3 пользователь Fabian Ducry написал:
>
> The error message is correct, you are not creating the structure that you 
> need.
>
> Let me illustrate this with the atom Cu 0 0 0:
>
> You request a periodic simulation with cell size ABC [angstrom] 3.810000 
> 3.810000 3.810000
> This implies that the Cu atom (0,0,0) is repeated every 3.81 angstrom in 
> every direction periodically. Because of this, a periodic image of the atom 
> also exist, for instance, at (-3.81,-3.81,-3.81).
> At the same time you specify the fractional coordinates for the first atom 
> in your structure with Cu -1 -1 -1, this is equivalent to 
> (-3.81,-3.81,-3.81).
>
> Because of the periodic boundary condition (PBC) you now have both atoms 
> at the same location, Cu 0 0 0 because of the PBC and Cu -1 -1 -1. 
> Therefore, the distance between these two atoms is 0.
>
> To fix this problem you can do the following:
>  - convert the scaled to cartesian coordinates
>  - increase the box size by a factor of 3
>  I.e.
> ABC [angstrom] 11.43 11.43 11.43
> and 
>       &COORD
>         SCALED FALSE
>         Cu -3.81 -3.81 -3.81
>         O -3.81 -1.905 -3.81
> [...]
>       &END COORD
>
> Best,
> Fabian
>
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