[gmx-users] Gradient electric field in GMX?

[David van der Spoel]

Yinghong wrote:
> Dear Dr. David:
>  
>  
>  >/ Dear Gmxers:
> />/ 
> />/ Is it possible to apply a gradient electric field in GMX, which is a
> />/ function of space? For example, field strength
> />/ in the left side of simulation box is set to zero, which gradually
> />/ changes to 1 V/nm in the right edge of box.
> />/ 
> />/ If yes, how to compile the source code? Thanks.
> /
>  > You can do periodic fields. Your version would have a discontinuous
>  > field at the box edge. Is that really what you want?
> Sorry, I forget the stuff of PBC. Take another example, field strength 
> increases from 0 V/nm in the
> left side of box to 1 V/nm in the middle part of box, and then decreases 
> to 0V/nm in the right edge. How
> to realize it?
>  
> What is your mean of periodic fields? As described in source code, we 
> can definie an electric field, which is
> varied as time. But at any specific time, field strength in the whole 
> system should be the same, right?
>  
> What I want to get is electric field is not uniform at any time, which 
> is different at different position in the system.
>  
Then you have to code it in sim_util.c routine calc_f_el
That should be straightforward to do.

>  
> // 
> Thanks and regards,
>  
> Xie YH
> Hong Kong University
> 
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se
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