How to correctly set the function in EXTERNAL_POTENTIAL?

[D Y]

Dear cp2k users and experts,

  I want to set up a function with spherical symmetry in CP2K_INPUT / FORCE_EVAL / EXTERNAL_POTENTIAL section during AIMD simulation, to prevent particles escape form slab. So i looked up the xTB manual for reference, and found there were two ways to set up such potential. one is logfermi potential, the other is polynomial potential. 

Hence, i set up something like these in cp2k input file:

1. &EXTERNAL_POTENTIAL

        ATOMS_LIST   129..138
        FUNCTION   A*(sqrt((X-a)^2+(Y-b)^2+(Z-c)^2)/R)^8
        PARAMETERS A R a b c
        VALUES     1.0E-2 5 9.2 10.8 5.6
        UNITS  eV angstrom angstrom angstrom angstrom
  &END EXTERNAL_POTENTIAL

2.   &EXTERNAL_POTENTIAL

        ATOMS_LIST   129..138
        FUNCTION   A*log10(1+exp(8*sqrt((X-a)^2+(Y-b)^2+(Z-c)^2)-R))
        PARAMETERS A R a b c
        VALUES     1.0E-2 5 9.2 10.8 5.6
        UNITS  eV angstrom angstrom angstrom angstrom
  &END EXTERNAL_POTENTIAL

I really want to know whether the above mentioned functions are correctly setted? if it is wrong, could you please tell me  how to correctly set up this function?

[sedate]

Hello, it is ok for seting a potential to prevent molecules motion during AIMD simulations? I get the same problem.