You can check it in the Charmm36 topology file. You may also define it if it is not already there.

Hi Soumya,

I have added a link of a paper with water-silica forcefield in CHARMM.

Article Water−Silica Force Field for Simulating Nanodevices

I think it might be OK. But if you still need more accurate value, you can use VMD Force Field toolkit plugin for parameterization. Since you mentioned silicon is present in an aromatic form, most probably parameterization might be better.

Thanks. Debasish, unfortunately, I couldn't locate the same in the topology file.

Soumyo, thanks, I'll take a look. :)

If you have a .pdb or .mol2 file for silicon atom already, you can generate topology and parameter files for it from charmm gui (http://charmm-gui.org/?doc=input/ligandrm).