# Re: Calculating gradient of the potential (force field) on each atom.

Date: Fri Jan 13 2017 - 11:34:11 CST

That is the correct way to get the forces (negative gradient of the
potential). Note that the result you get should be independent of the
velocities, unless you have Langevin forces. To avoid that, I would set
the temperature to 0.

On 01/12/2017 05:37 PM, Wasut Pornpatcharapong wrote:
> Hello all,
>
> I would like to calculate the gradient of the potential (\grad V) on each atom and tried putting,
>
> output onlyforces file
>
> and wonder if this line in the configuration file gives me the force on each atom due to the potential. I would like to exclude the translational forces. If this does not work the way I intended, could you please suggest a way to compute the gradient of the potential on each atom given the coordinates, velocities, and the parameter file?
>
> Thank you,
>
> -Wasut
>

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