[gmx-users] multiple electric fields

David van der Spoel spoel at xray.bmc.uu.se
Sat Oct 27 12:15:11 CEST 2018

Den 2018-10-26 kl. 07:46, skrev Alex:
> As expected, multiple instances of a given component are not accepted by 
> Gromacs. Is there anything that can be done? Can the functional form be 
> extended to the current form + constant offset?
> The use scenario is very simple: photosensitive solid-state ion 
> channels. It is that relatively rare instance when there is no chemical 
> reaction that results in photosensitivity, so one needs a constant 
> driving field and an additional sinusoidal wave. We can set this up with 
> LAMMPS, but our timescales will drop by a factor of five... Anyone?
I would propose you add the constant in the code for now and work with 
it. If it works well please upload a redmine issues with a feture request.
You literally have to add somewhere
field = field + c
check src/gromacs/applied_forces/electricfield.cpp

> Thanks,
> Alex
> On 10/25/2018 1:08 PM, Alex wrote:
>> Hi all,
>> Is it possible to have an electric field of the form described here: 
>> http://manual.gromacs.org/documentation/2018.1/user-guide/mdp-options.html#mdp-electric-field-x%20;%20electric-field-y%20;%20electric-field-z 
>> but with a constant component?
>> In other words, for a given component (x,y, or z): E0_1 + 
>> E0_2*something-sinusoidal? For instance, can we have multiple 
>> 'electric-field-z' statements, each describing the desired portion?
>> Thanks,
>> Alex

David van der Spoel, Ph.D., Professor of Biology
Head of Department, Cell & Molecular Biology, Uppsala University.
Box 596, SE-75124 Uppsala, Sweden. Phone: +46184714205.

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