[gmx-developers] g_dipole: dipole moment autocorrelation function

[David van der Spoel]

On 2011-03-22 21.39, Nilesh Dhumal wrote:
> Hello,
>
> I wrote to gmx-users many times but never got reply.  I am posting this
> message to developer.
>
>
> I am trying to calculate the non normalized dipole moment autocorrelation
> function for water. I am using flexible spc water model
> (define=-DFLEX_SPC). I am using gromacs 4.0.7 version.
>
> I run the simulation for 4 ns.  I run the following command to calculate
>   the dipole moment autocorrelation function
>
>   g_dipoles -f water.trr -s water.tpr -nonormalize -corr total -c
>
> I am geting the value really high starts from +5000 to -100 (dipcorr.xvg).
>
> Is there anything wrong and function is not geting converge to zero.
>
> Thanks
>
> Nilesh
>
>
>
You turned off the normalization. It does fall off to -100/5000 = -0.02 
if you would normalize.


-- 
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