Hi Live King, I think the temperature coupling strongly effect on your observation since the velocity of atoms (ions) will be rescale after every tau-t value. It means the movement direction of ion under EEF will be mostly canceled for every tau-t (ps). If you set tau-t to be larger than default value (.i.e 10, 100 or 1000) you can see the effect of EEF on your system.
Viet Man, University of Pittsburgh School of Pharmacy > > Dear David and Harutyun, > > Thanks for your reply. Density plots were the first check I did. They show > a very minor difference. I imagined that the electric field is not > sufficient, however, presence of high electric field ( > 1 V or 1000mV)* > disrupts the membrane and my simulation crashes*. Is there any solution to > this problem? I will have a look at compel. > > On Thu, Feb 13, 2020 at 6:21 PM Harutyun Sahakyan <h_sahak...@mb.sci.am> > wrote: > >> 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_sahak...@mb.sci.am >> sahakya...@gmail.com >> >> February 13, 2020 2:07 AM, "Live King" <vikasdubey1...@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, -- Gromacs Users mailing list * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before posting! * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists * For (un)subscribe requests visit https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or send a mail to gmx-users-requ...@gromacs.org.