[gmx-users] Replica Exchange for surface tension

[gozde ergin]

I use Charmm36 force field. Do you mean the force field parameter between cocobetaine and SDS? Because for pure surfactant I am able to estimate the correct surface tension. Which means force field parameter of SDS-water and cocobetaine-water is fine.

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> On 28 Mar 2017, at 7:21 PM, Justin Lemkul <jalemkul at vt.edu> wrote:
> 
> 
> 
>> On 3/28/17 12:43 PM, gozde ergin wrote:
>> I have a mixed system of SDS and cocobetaine on water surface.
>> I estimated the surface tension of SDS on water surface and cocabetaine on surface tension separately and correctly (comparing with experimental results).
>> However I could not estimate the correct surface tension for SDS-cocobetaine mix in even 150 ns simulation.
>> Do you think replica exchange simulation would help me to estimate the correct surface tension of mixed system?
>> Do you have any idea why I failed in estimating the mixed system surface tension?
>> 
> 
> If a physical model fails to produce known physical properties, the problem is often the model itself.  I'd suspect the force field parameters first.  What is the source of your parameters?
> 
> Replica exchange helps you get over large barriers to improve sampling, but I doubt that's useful here in a mixture of small molecules.
> 
> -Justin
> 
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> Justin A. Lemkul, Ph.D.
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