[gmx-users] calculation of surface tension of a polymer surface_2

[Gyorgy Hantal]

Hi,

The surface tension computed in gromacs is the integral of the difference
of the normal (Pzz) and lateral ((Pxx_Pyy)/2) pressure components along
direction z. This gives you 0 in an isotropic bulk but something positive
at the interface.
The surface tension is basically the surface free energy, not the surface
energy.
To get the surface energy, you also need to run a simulation for a
crystalline bulk and compare the average energy of this system with that
containing the two interfaces.

Does that help?
regards
Gyorgy

On Fri, 22 Feb 2019 at 12:14, Maria Luisa <ml.perrotta at itm.cnr.it> wrote:

>
> Dear all,
> I've a question. I've a PVDF polymeric membranes, for which I'd like to
> calculate its surface tension. I performed a MD simulation of
> crystallization and I'd like to know if it's possible if there's a method
> to evaluate surface energy.
>
> With command gmx energy, there's the possibility to calculate Surf*Surf
> Tens. But at what is it referred?
>
> Thank you to all in advance.
>
> Maria Luisa
>
>
> Maria Luisa Perrotta
> Ph.D Student, CNR-ITM
> via P.Bucci, 87036 Rende (Cs)
> Italy
> email: ml.perrotta at itm.cnr.it
>
>
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-- 
---------------------------
Gyorgy Hantal, PhD
Postdoctoral Fellow
Dept. of Computational Physics, University of Vienna
Sensengasse 8/9, 1090 Wien, Austria
gyorgy.hantal at univie.ac.at <gyorgy.hantal at gmail.com>
Tel. +43-(0)1-4277-73292