Hi all<br><br>I had simulated water-ccl4 (ccl4-water-ccl4) interface and measured
the interfacial tension in NVT ensemble and i found a average value to
be 97.0615 mN/m (correct me if iam wrong) and divided it by two (because
i had two surfaces) to get the interfacial tension of single
liquid-liquid interface and the value was found to be 48.530 mN/m which
is close to the experimental value of 44.3 mN/m. <br>
<br>Energy Average RMSD Fluct. Drift Tot-Drift<br>-------------------------------------------------------------------------------<br><div id=":13r">#Surf*SurfTen 970.615 4684.12 4672.71 -3.77379 -1132.15<br>
<br>1. My question is in which ensemble one should measure the interfacial tension NVT (or) NPT and why?<br><br>2.
Can one use surface tension coupling option in gromacs to measure the interfacial tension
of
liquid-liquid interface.If so, what should be the parameters in the
pressure coupling section. I have gone through the manual but not able
to understand it clearly such as what value one should give for ref_p
and other parameters in the pressure coupling section? <br>
<br><br>I used g_analyze to estimate the standard error (error estimate)
in the surface tension values by using the sf.xvg file obtained from
NVT simulation and it says fitted parameter is negative and invalid fit
below is my error message and i don't what is going wrong.<br>
<br><br> std. dev. relative deviation of<br> standard --------- cumulants from those of<br>set average deviation sqrt(n-1) a Gaussian distribition<br>
cum. 3 cum. 4<br>SS1 3.835787e+02 5.051521e+03 4.124550e+02 0.321 0.713<br><br>a fitted parameter is negative<br>invalid fit: e.e. -nan a 0.994955 tau1 1.50734 tau2 -8.62581e+08<br>
Will fix tau2 at the total time: 300<br>a fitted parameter is negative<br>invalid fit: e.e. -nan a 1.00655 tau1 1.72207 tau2 300<br>Will use a single exponential fit for set 1<br>Set 1: err.est. 529.855 a 1 tau1 1.6613 tau2 0<br>
<br><br>3. How to use g_analyze to get the standard error correctly?<br><br>any help regarding my questions are greatly appreciated.<br><br>Regards<br>Vinothkumar<br>
Research scholar<br>IIT Madras<br>Chennai 600036<br>India<br><br></div>