[gmx-users] Can't observe ion separation under the influence of electric field

[Harutyun Sahakyan]

You can use compel and build a double bilayer system to separate ions. However, if you separate positive and negative ions, you will have very high membrane potential, event two ions difference can raise potential about 200 mV. In your case, I suppose 500 mV is not enough to separate all ions in a PBC box. 

https://www.mpibpc.mpg.de/grubmueller/compel 



Harutyun Sahakyan
Senior Assistant at Laboratory of 
Computational Modeling of Biological Processes, 
Institute of Molecular Biology, NAS, Armenia, Yerevan
Tel: +374 93 323990
h_sahakyan at mb.sci.am
sahakyanhk at gmail.com

February 13, 2020 2:07 AM, "Live King" <vikasdubey1008 at gmail.com> wrote:

> Dear all,
> 
> I am running a simple test case with a lipid bilayer (DMPC), water, and
> ions (150mM KCL) under the influence of a constant electric field ( 300mV,
> 500mV, and 700mV). *I expected positive and negative ions to separate in
> the presence of an external electric field*. However, I am not observing
> such behavior despite running the all-atom simulation for 400ns in any
> case. I am using gromacs 2018.2, my mdp file is standard charmm-gui
> production with electric field option.
> 
> for example 500mV electric field in Z-direction :
> electric-field-z = 0.060 0 0 0 ; *500**mv = 8.25nm* 0.060 =
> 500 mV *
> 
> Are there any settings to run the electric field simulation that I miss?
> Any help will be greatly appreciated.
> 
> Thank you,
> -- 
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