[gmx-users] spc water pressure VS density

[David van der Spoel]

On Fri, 2005-07-29 at 12:33 -0300, Lin Zhen wrote:
> Dear all
> 
>     I have been doing some simulation on the spc water in the gromacs
> package. I used editconf -density to get different densities, then run
> it over 1000000 steps, and use g_energy -sum to get the average of the
> pressure. But all pressure we get are about 16 MPa or -10 MPa, close
> to zero.
> 
> Because pressure should increase a lot as the density increase, but i
> didn't see that, is there anything I did wrong?

I've done it the other way around: couple to different pressures and
measure the density. You can compute the compressibility that way.
> 
> Thank you very much!
> 
-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
spoel at xray.bmc.uu.se    spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
spoel at xray.bmc.uu.se    spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++