[gmx-users] biphasic simulation and surface-surface tension calculation

[James Lord]

Hi all,

I have done two simulations following Justin's tutorial for biphasic
systems one with cyclohexane-water and the other one with a protein in
water phase that diffuses and comes to the cyclohexane-water interface at
some points and stays there for the rest of simulation. When I calculate
the surface tension as a function of time for cyclohexane-water system it
fluctuates a lot but when I average it over the time of simulation it is
giving me a reasonable value which matches with experimental one. But for
the simulation that I have protein, it is again just giving me the surface
tension of two liquids while I was expecting the surface tension to
decrease upon protein adsorption at interface (this is the case
experimentally, as the protein acts like a surfactant)?  Does anyone have
experience with such a system? any comments is much appreciated.

Here is what I am doing to get surface-surface tension

g_energy -f energy.edr -s md.tpr -o surften.xvg

selecting #Surf*SurfTen when asked


Cheers
James