[gmx-developers] Surface tension of bulk water

[Berk Hess]

Hi,

Please post user questions to the forum: 
https://gromacs.bioexcel.eu/c/gromacs-user-forum/

But your problem is that you should simulate a box with 
liquid+gas/vacuum phase so it has interfaces, not bulk liquid.

Cheers,

Berk

On 07/08/2020 10.12, Abhinav Srivastava (P14CHM002) wrote:
> Dear Gromacs Users,
>
> I am trying to calculate the surface tension of bulk water. I am using 
> TIP4P/2005 water model consisting of 851 water molecules. The box 
> dimensions are *3.71233   3.71233 1.85616.*
> Following are the parameters for the mdp file which I am using:
>
> ; OPTIONS FOR WEAK COUPLING ALGORITHMS
> ; Temperature coupling
> ;Tcoupl                   = no
> Tcoupl                   = nose-hoover
> tau_t                    = 2.0
> ref_t                    = 308
> tc-grps                  = system
>
> ;Pcoupl                   =  no
>
> Pcoupl                   = Berendsen
> tau_p                    = 2.0
> pcoupltype               = isotropic
> ref_p                    = 1
> compressibility          = 5e-5
>
> I am using *#Surf*SurfTen* option in the g_energy command in 
> GROMACS-4.6.5. I have calculated surface tension for 70 ns NPT run. 
> Following is the output which I am getting:
>
> Statistics over 35000001 steps [ 0.0000 through 70000.0000 ps ], 1 
> data sets
> All statistics are over 350001 points
>
> Energy                      Average   Err.Est.       RMSD  Tot-Drift
> -------------------------------------------------------------------------------
> #Surf*SurfTen              -3.53622        2.6    1336.67 0.561131 
>  (bar nm)
>
>
> The value for surface tension of bulk water at 308 K is 70.38 dyn/cm.
>
>
> Kindly tell me whether I am giving some wrong input parameters?
>
>
> Regards,
>
>
> -- 
> *Abhinav Srivastava*
> /Research Scholar/
> Indian Institute of Technology, Jodhpur
> Rajasthan
>

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