Dear lampps users,
In my project, I was modeling the formation processes of Ni catalysts on a SiO2 crystal substrate. What potential parameters best describe the interaction between Si-Si, Si-O, O-O, Si-Ni, Ni-Ni and Ni-O atom pairs?
thanks for the reply,
Ibrat
First, I don’t think you will get a very accurate description of this kind of system, when using only pairwise additive potentials.
Second, have you checked what the surface of the \mathrm{SiO_2} should look like? Are you sure there are no exposed oxygen atoms that would become OH groups?
Third, I would expect that you may need to us some model that can represent the polarization of the different atoms at the interface, since you have a polar surface.
Finally, the best way to find possible choices of potentials, is a thorough survey of the published literature. You need to learn from the experiences that others have made for the same or similar systems and apply them here. Then, of course, you need to set up simple/small test systems to confirm whether you get reasonable results, e.g. in comparison of DFT calculations for the same system. This should also give you a gauge on the magnitude of errors that come with classical models for “difficult” systems.
First of all, thank you very much for the answer. I previously prepared the SiO2 substrate using VESTA and minimized its energy in LAMMPS, heating it to a certain temperature. In this case, I used Tersoff to represent the interaction of SiO2 atoms, MEAM to represent Ni-Ni when depositing Ni atoms on the surface, and Lennard-Jones potential parameters to represent Si-Ni (of course, based on existing literature). But the problem is that these potentials are not reactive and cannot represent bulk diffusion of Ni as a result of deposition on Si or SiO2 surface. There is no reductive force field covering all these atoms. Since different values of these potential parameters are used in the literature to model such systems, I am not sure which one is the most optimal.
This doesn’t address my concern about the \mathrm{SiO_2} surface and the only Tersoff potential parameterization I know for \mathrm{SiO_2} is only suitable for bulk systems. So you very likely will have gotten bogus results.
That statement does not make much sense. What kind of “reaction” are you looking for? What do you mean by “bulk diffusion” when you are talking about depositing metal atoms on a surface?
What is a reductive force field?
Nobody can know this without making careful tests.
Please note, that what you are asking about is not really a LAMMPS problems but rather a problem of the science of your research and the methodology you need to be using and generally about how to plan and set up simulations of complex problems. This makes it a topic for a discussion with your adviser/tutor/mentor or knowledgeable colleagues. It is very difficult to advise on these issues from remote and without being familiar with the details of your research.
I got you. Thank you very much for your advice!