[gmx-users] Surfactant from experiments to MD simulation

André Farias de Moura moura at ufscar.br
Wed Apr 10 23:59:35 CEST 2019

Hi Alexander,

besides being really hard to achieve the um scale, the timescales also tend
to be too large for that kind of system, so direct atomistic modelling
might just be useless here even if you get the model drawn. The size of the
trajectory might easily become too large to be properly analyzed later.

in principle CG might help to achieve both a larger length scale and a
longer timescale, but I guess that you would be still far from the
experimental regime, so maybe it is not that helpful.

if the actual size and timescales cannot be properly reached then I would
go for simplified models depicting details of the actual system of
interest. For instance a periodic model system of your material with a few
nm in edge length could be used to study the adsorption patterns of the
surfactant. If the material has well-defined crystalline structure, then
different faces would have to be considered.

Although indirect, these simulations might provide evidence for the
stabilization mechanisms.

I hope it helps.


On Tue, Apr 9, 2019 at 11:53 PM Alex <alexanderwien2k at gmail.com> wrote:

> Dear all,
> My question below is not directly a Gromacs's technical issue, so sorry for
> posting it here, however, any comment would be highly appreciated;
> A long surfactant (Molecular Weight (MW) of around 1200 g/mol) with weight
> fraction of 0.8 % in the system of emulsion works to keep the particle's
> size of a material around 1 micrometer (um) of diameter experimentally.
> To model such emulsion in all atoms MD simulation we can't go for the
> particles of 1 um diameter, but far less to a particle with around only 7
> nm of diameter. From 1 um particle in experiment to 7 nm one in MD
> simulation, the surface-volume of particle gets change, so that, using the
> surfactant with similar MW and weight fraction as the ones used in
> experiments does not work in MD simulations, so, would you please share
> your idea and though on how to mimic the MD simulations to experiments as
> mush as possible?
> Best regards,
> Alexander
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Prof. Dr. André Farias de Moura
Department of Chemistry
Federal University of São Carlos
São Carlos - Brazil
phone: +55-16-3351-8090

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