[ESPResSo] Position-dependent Langevoin thermostat (was: Re: Scenario Form)

[Olaf Lenz]

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Hi Lorenzo!

Lorenzo Isella wrote:
> There is a fundamental problem with this approach: once a monomer is
> surrounded by other monomers, it should feel a different noise due to
> the screening by its neighbors, but this effect is not accounted for
> in Espresso. I refer to the case in which there is no shear, just
> Brownian motion.
> Nobody knows exactly what it should feel, but it would be (at least
> for me) wonderful to have a feature in Espresso that allows me, while
> keeping the overall system temperature around T, to have the noise on each
> monomer in an aggregate expressed as a function of e.g. the number of
> first neighbors of that monomer.

The Langevin thermostat has been constructed as is to model the
statistical NVT ensemble, while still being very simple.
I think that if you would modify the Langevin thermostat in that way
without exactly knowing what you're doing, you would mess up this
statistical ensemble that your simulation lives in, and I wouldn't
expect that any of the effects that you might see in such a simulation
has any resemblance to what happens in nature.

As for whether there might be useful alternatives for you, I think that
others on this list have a better founded opinion on this matter.

Olaf
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