[gmx-users] dielectric constant of water by gromacs

[David van der Spoel]

On 2014-05-29 06:07, 来者可追 wrote:
> Dear David,
>    I have a problem when simulating the dielectric constant of water
> according to g_dipoles.I used the water file in "tutor"(216 SPC waters),
> when I write the program "g_dipoles", the result is as following, why
> not Epsilon about 65?
>
> ‍=================================
> Finite system Kirkwood g factor G_k = 0.163272
> Infinite system Kirkwood g factor g_k = 0.123058
>
> Epsilon = 3.83011
> ‍‍=================================
>

Did you use PME? In that case it should work.
If you used a cut-off you have to redo the simulation.


>
>    I cannot understand " you have to give extr options, depending on how
> you did the simulation. g_dipoles -h (hint look at the epsilonRF
> option). If you used a cut-off then you will not get the right
> dielectric. " (
> https://www.mail-archive.com/gmx-users%40gromacs.org/msg18306.html ) Can
> you explain it more for me? Thank you so much!
> ‍‍‍‍‍‍‍
>
> Sincerely,
> LiBin
>
>


-- 
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