I was trying to perform lipid bilayer MD for my protein based on GROMACS's Membrane Protein Tutorial.
I can successfully orient the protein in the lipid (turquoise) as you can see in the image below:
But I would like to control the thickness A, B, C of the lipid (before the actual MD run), since I'd like to allow some area of the protein to be exposed outside the lipid (they're extracellular region of the protein).
How can I achieve that with GROMACS?