Hi, I have a question about the definition of Force field in Lammps, what is the indicator for selecting force field?
Can I use the meam Li Co O potential to define the interaction of oxygen and cobalt to simulate a membrane doped with a cobalt atom in adsorption? Or, for example, can I use the sio tersoff potential for the oxygen molecule? Or can I use the BNC tersoff potential for the nitrogen molecule? Why is the Leonard Jones Force Field used in most articles?
In reverse order:
The Lennard-Jones functional forms are widely used because they have a good trade-off between realism and speed. For example, you calculate the 12-6 LJ energy by finding r^{-6} and then squaring it immediately gives you the r^{-12} term. Also, they were historically some of the first force-fields developed, and it’s cozy and familiar the long history of literature using LJ force fields means that it can be easier to spot your mistakes by comparing your results to past papers.
You can always try to find more realistic force fields, at the cost of them being slower. You will not know if your force field is more or less realistic unless you have some other “ground truth” to benchmark some results of your simulations. Also, most force fields will reproduce some aspects of your system’s real-world behavior but not others.
For example, most LJ parameters for water give the wrong melting point (Vega 2005), so you will most likely not get good results using them to simulate ice nucleation.
As another example, protein force fields and parameters are often validated against X-ray diffraction data. But it has previously been much easier to obtain such data for ordered rather than disordered proteins, so you cannot trust old force fields too much if you are simulating a disordered proteins and need to use some cutting-edge versions (Zerze 2019).
Thus, there are only two ways to proceed. The first way is to obtain experimental data for your system of interest, relevant to your phenomenon of interest, and then perform enough simulations to convince yourself (and your reviewer) that the force field and parameter set you have chosen replicate said experimental data to your desired accuracy. The second way is to hope and pray that someone has already done all that, and cite them.
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thank you so much srtee.