[gmx-developers] Time Dependent Electric field

David van der Spoel spoel at xray.bmc.uu.se
Tue Jan 7 14:43:38 CET 2014

On 2014-01-07 12:30, ryo kawakita wrote:
> hi, i am new to gromacs. i was trying to use the time dependent Electric
> field and found that there is no direct way to use it, so tried to go to the
> source code(sim_util.c calc_f_el) and modify a little bit so that i can use
> it for my purpose.
It works fins as far as I know, but the documentation is somewhat 
lacking. You can have a (pulsed) oscillating electric field with the 
right combination of input options.
See Carl Caleman and David van der Spoel: Picosecond Melting of Ice by 
an Infrared Laser Pulse - A Simulation Study Angew. Chem. Intl. Ed. 47 
pp. 1417-1420 (2008) for an application.
> so i went into the sim_util.c and in the calc_f_el portion...
> i tried to modify the lines
> Ext[m] * = Ex[m].a[0]*FIELDFAC;
> into
> Ext[m] *= Ex[m].a[0]*FIELDFAC*sin(2*180*frequency*t);
> But it showed no change in the output.
> Tthats why i tried to see if it is really working or not and put  Ext[m] * =
> Ex[m].a[0]*FIELDFAC* 0 (multiplied the whole with a zero);.
> It did not work either (ie. electric field was still working)
> --
> View this message in context: http://gromacs.5086.x6.nabble.com/Time-Dependent-Electric-field-tp5013625.html
> Sent from the GROMACS Developers Forum mailing list archive at Nabble.com.

David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se

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