[gmx-users] Re: g_velacc

David van der Spoel spoel at xray.bmc.uu.se
Fri Jul 5 11:10:11 CEST 2013

On 2013-07-05 10:50, Ishwor wrote:
> I have taken the fit for 2ns in Einsteins curve to calculate the diffusion
> coefficient but when i take the values up to 100 ps for velocity auto
> correlation i get the matching result...Is it good to do such thing? i will
> be happy if you guide me.
> I have attached the graph of VAC herewith.
> Thanks <http://gromacs.5086.x6.nabble.com/file/n5009582/vac.jpeg>
> --
> View this message in context: http://gromacs.5086.x6.nabble.com/g-velacc-tp5009541p5009582.html
> Sent from the GROMACS Users Forum mailing list archive at Nabble.com.
The graph does not show the tradition ripples. If this is for water the 
result could be ok with 100 ps, but you still need to have decent 
sampling (e.g. 20 fs) of the velocities since they change rapidly.

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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