Determination of potential constants in a polymer chain (bond, angle, dihedral...constants)

[thinhgt18]

Hi,
I'm new in MD simulation. I have a question: how to determine the force constant in a polymer chain?. Example I have a bond, angle harmonic and dihedral multiharmonic with parameters corresponds. How can I calibrate thess parameters. Could you suggest me some articles or books for reference.
Thank you.

[Enthalpy]

If you're willing to spend a few years measuring and modelling many compounds, then you can create your own model. Presently there are very few ones (like AM1, PM3, MND0...) because the task is difficult. If you hoped an answer like "it's cosine times polynomial", just forget it and use the standard models cited above.

 

Depending on how serious your work shall be (MD tends to be extremely simplified to be able to run) you can define more rudimentary models, like atoms being hard spheres, or interaction potentials as polynoms of 1/R, and bonds having some stiffness...

 

The detailed knowledge about such atoms behaviour is concentrated in the models cited above - no idea if someone has published it on paper, as this would make much volume and a boring read. So you might observe what AM1 tells and deduce a simplified model for each bond or intermolecular force... Knowing that many such force fields are themselves deduced from orbital simulations (aka "first principles"), one may wonder how much science is in a model cascade of nothing measured.

 

Let's see if more optimistc forum members pass by...

[thinhgt18]

Thanks for your response.

In my simulation, I am trying to increase the temperature at equilibrium. I think these parameters depend necessarily on the chosen temperature. So for us, it is dificult to find new parameters. I am looking for right now in the literature if we could find some ideas.