A question about Pair_style

Dear Lammps users ,

I try to calculate free energy by FEP method for Water with TIP4P model .
As you know we should use soft potential for defining the interaction between solvent-solute .
When we want to calculate FEP for water we can have one molecule as solute and others as solvent !

Now I was wondering how I can define the O-type and H type in lj/cut/tip4p/long/soft pair-style ?
Because in this special system we have two different type of oxygen and also two different type of hydrogen !

Thanks for your attention,