Specify the center of the grid based on a molecule's center or absolute coordinates for a mg-manual multigrid calculation. The syntax is:

     gcent { mol id | xcent ycent zcent }

where the user can specify either:

mol {id}

Center the grid on molecule with integer ID id; as assigned in the READ section. Molecule IDs are assigned in the order they are read, starting at 1.

or the user can specify

xcent ycent zcent

The floating point coordinates (in Å) at which the grid is centered. Based on the PDB coordinate frame.