I am trying to simulate a glycoprotein and generated GROMACS input files using CHARMM-GUI Input Generator (Glycan Reader).

My molecule is large and I want to use a 4fs time step for the simulation. for this, I have to make the topology with the virtual sites for H atoms.

I couldn't figure out how to make the Input Generator to do that! Can anyone point out if there is such an option in it?!

Thank you.