[gmx-users] electric field

[Man Hoang Viet]

Hi,

I can confirm electric field (even laser-pulse form) in GROMACS (all
version from 3.0 to current newest one) work fine. To check it, you may
consider a system containing only an ion (say Na+) in vacuum and set mdp
file as:
#######
dt                  =  0.0002    ; ps !
nsteps              =  100  ; total 20 fs

...

Tcoupl              =  no
Pcoupl              =  no
gen_vel             =  no
E-x                 =  1 30 1
####

After run MD you may check the velocity of the ion and see how it work by
some general motion equations such as Force = -q*E = m*a -->
veleocity=a*t.

Additionally, the option -field of mdrun will give output of electric field.

Good luck!

Viet Man


> Date: Sun, 15 Nov 2015 22:58:34 +0330
> From: Maryam Kowsar <maryam.kowsar at gmail.com>
> To: gromacs.org_gmx-users at maillist.sys.kth.se
> Subject: [gmx-users] electric field
> Message-ID:
> 	<CAK1iX1UrqgQ61-VCbEg8-dMLjQXs+6KuERQ7m47SzxFy4ubk=A at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Dear users,
>
> I applied electric fields of different magnitudes (less than 1 v/nm since
> higher amounts are avoided) in my system. I have some charged water
> molecules and I expected to see very different results when the magnitude
> is changed, but haven't got that much difference. How can I be sure that
> electric fields worked?
> I found the following link that it changed the code of electric field
> according to the shape of the system:
>  http://www.gromacs.org/Developer_Zone/Programming_Guide/Patching_mdrun
> Can the current implemented code in gromacs be applied for all systems or
> should I change it for different systems?
>
> Thanks!