[gmx-users] g_dipole: dipole moment autocorrelation function

[David van der Spoel]

On 2011-03-30 18.54, Nilesh Dhumal wrote:
> Hello,
>
> I am trying to calculate the dipole moment autocorrelation
> function for my system (ionic liquid). 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 -corr total -c
>
> The function is not geting converge to zero.
>
> I want to use this data for calculation of power spectra by fourier
> transfom of dipole moment autocorrelation function.
>
> Can you tell why its not geting converge to zero?
>
You have to simulate at least a few 10s of ns for such slow liquids to 
converge. Alternatively you can average over many independent 
simulations (10s).
>
> Thanks
>
> Nilesh
>
>
>


-- 
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