[gmx-developers] Surface tension of bulk water

[Abhinav Srivastava (P14CHM002)]

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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