Fixing positions of multiple atoms with different constraints

[Rafael Soler-Crespo]

Hi all,

I am trying to do a calculation in which I fix the edges of a sheet (graphene) with different boundary conditions. The calculation is a geometry optimization. The left and right ends of the sheet are constrained to not move in the x direction. The top and bottom parts of the sheet are constrained to not move in the y direction. However, due to how the FIXED_ATOMS section works in CP2K I cannot create different constraints for each end of the sheet (in other words, I am forced to use a global constraint which I do not want). Does anyone know any way to get around this?

For example, I would like to do:

   LIST                                1 2 3 4

   COMPONENTS_TO_FIX    XY

   LIST                                 5 6 7 8

   COMPONENTS_TO_FIX    YZ

However, the code won't let me do that (the keywords appear twice).

Any help will be greatly appreciated.

Thanks,

Rafael

[Ari Paavo Seitsonen]

Dear Rafael,

  Would it work like

    &FIXED_ATOMS

   LIST                                1 2 3 4

   COMPONENTS_TO_FIX    XY

    &END FIXED_ATOMS

    &FIXED_ATOMS

   LIST                                 5 6 7 8

   COMPONENTS_TO_FIX    YZ

    &END FIXED_ATOMS

it with multiple &FIXED_ATOMS ... &END FIXED ATOMS sections?

    Greetings,

       apsi

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  Ari Paavo Seitsonen / Ari.P.S...@iki.fi / http://www.iki.fi/~apsi/
  Institut für Chemie der Universität Zürich
  Tel: +41 44 63 55 44 97  /  Mobile: +41 79 71 90 935

[Rafael Soler-Crespo]

Dear Apsi,

Just for reference for future users of the code, yes, your solution indeed works.

Thanks for the tip!

Rafael