[gmx-users] high pressure and temperatures: force field parameters

[Mohsen Ramezanpour]

Hi Sotirios,

I totally agree with what you said. However, I am not interested in
breaking bonds or forming bonds (e.g. in plasma case)

To clarify the question, here is an example:

How if you want to check the effect of high temperature on protein
structure (folding and unfolding problem)? Or if you want to do a simulated
annealing! How much are you allowed to raise the temperature?!
(for now, lets assume unfolding and folding can happen in allowed time
scales. Lets focus on ff validity for a moment)

Is the ff developed for proteins are valid in high temperatures? We know
they are working well in physiological range. However, there are some cases
of interest where high T happens.

Hope it is clear now. The same for pressure.

Cheers
Mohsen

On Thu, Sep 8, 2016 at 10:42 AM, Sotirios Dionysios I. Papadatos <
si.papadatos at edu.cut.ac.cy> wrote:

> I am not aware on your question per se, but just to give you food for
> thought. Force fields are not based on real values of let's say force
> constants. You can't produce for example 'plasma' at least with the default
> ff, if you overheat. So it not a matter of a ff not being accurate for high
> values of T or P, rather than a ff is made to reproduce - simulate the
> physical properties of a system as close as possible to real life
> conditions. Now, if you are interested in simulating on such high values,
> you should search if there is a literature on how to simulate in such
> environments specifically.
>
> ________________________________
> From: gromacs.org_gmx-users-bounces at maillist.sys.kth.se <
> gromacs.org_gmx-users-bounces at maillist.sys.kth.se> on behalf of Mohsen
> Ramezanpour <ramezanpour.mohsen at gmail.com>
> Sent: Thursday, September 8, 2016 2:47:07 AM
> To: Discussion list for GROMACS users
> Subject: [gmx-users] high pressure and temperatures: force field parameters
>
> Dear gromacs users,
>
> Force field parameters are not usually parametrized for high pressures and
> temperatures.
>
> say for P=500 bar! or for T=500 K
>
> Although we can do simulations, but we cannot trust on the results.
>
> Is there any maximum (or range ) defined somewhere in the literature (which
> I am not aware of) we should not go further in simulations?
> I searched but I did not get any good answer for it.
>
> The best way would be to check the force field validity by comparing the
> simulations (with that FF) in desired high T and P with some available
> experimental data, even if these systems are not the same with what you are
> interested in. If they are valid, so, we might do predictions for our
> system of interest in those T and P range. Well, this also can be argued,
> because, the force field might not work properly for our specific molecules
> in question.
>
> Please let me know your opinion
>
> Thanks in advance
>
> Cheers
> Mohsen
>
>
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