The system I want to simulate is a benzene ring molecule sandwiched by Al2O3 nano-rod on both sides along the z axis. There is no chemical bonding between benzene ring and the Al2O3 compound.
What type of potential should I choose for such system? Can I choose the pair_style reax/c for the C-Al atom; and pair_style lj/cut 3.0 for C-C atoms; pair_style lj/cut 2.0 for Al-O atoms. Does it make sense?
Do I also need to set bond_style for Al-O atoms and C-C atom because the chemical bonding between Al-O and C-C does not break during the simulation? If so, what type of bonding style should I choose for such system?
I did not find any literature reference discussing such system. Would anyone please give me some suggestions/comments?
When you have no force field for a given system, the proper way to proceed would be to derive one yourself. There are different methodologies to do so, each usually striving to reproduce a specific reference feature/property of the system.
There exist some force fields out there that are “generic”, meanign that they have been developed to be able to model many different systems (to some extent or another). If you do not have time to derive a force field yourself, using a generic one could be a possibility. Although note that the accuracy in reproducing property X or Y of your system is in principle lower when using a generic force field compared to a specific one, so depending on what your goal is, it might not be a good idea.
Also, you need to take into account that you have a “non bulk” phase in the Al2O3 phase (the nano-rod thing), and thus a force field derived in the context of bulk materials may not be suitable.
Since you are new to LAMMPS, you need to start with something less complex to get “a feeling” for what can work and what doesn’t. To start with a complex multi-component system for which you can find no published potentials is a recipe for disaster and personal doom.
A simple step would be to figure out how to simulate each component separately.
Will this be in vacuum or with a solvent?
I see no mention of hydrogen atoms. Are you sure you \mathrm{Al}_2\mathrm{O}_3 nanorod has no OH groups on the surface?
That depends on the model used to represent each sub-system.
If there was already a publication describing exactly what your project is, there would not be much value to your project. So you have to be a bit more creative and look for simulations of parts and of somewhat similar setups.