Periodic slab preparation

GROMACS version: 2021.4
GROMACS modification: Yes/No
Here post your question
I want to import a silica slab from materials studio into gromacs. But I don’t know how to convert the slab generated into a gromacs compatible format (either pdb or gro) as they are both non-periodic file formats. This has created problems with energy minimization (very high potential energy, of the order of e+35) and hence, the system is not converging.