Re: [ESPResSo] trouble with tabulate potentials

[Olaf Lenz]

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Hello!

강지원 wrote:
> I made a potential with structurual distribution fuction of all-atom MD 
> simulation results. 
>  
> With that potential i got these series of message 
>  
>  {086 particle coordinate out of range, pos = -28235093640131156.000000, 
> image box = -2147483648} 
>  
> I have no idea to make a correct numerical potential form.
>  
> If you have any example or guideline for using table potential form,  please 
> help me.

Sorry for answering late.
It is hard to answer your question, given so few information about your
setting.

The error message looks as though your system is exploding, which
usually means that a particle experienced a very huge force. This can be
caused either by a wrong definition of the potential, or because two
particles were too close to each other.

To check the first case, you will find examples of tabulated potentials
in the ESPResSo-distribution in the files

        testsuite/lj1.tab
        testsuite/lj2.tab
        testsuite/lj3.tab

Furthermore, the documentation of the command "inter tabulated" should
give you enough information to work with.

In the second case, you will have to see to it, that none of the
particles are too close. To do that, you can either set up the system so
that they don't, or you'll have to go through a warming up procedure
(others call it energy minimization), where you very slowly increase the
strength of the potential, so that the forces grow slowly.

Best regards
        Olaf


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