Solvation free energy computation by g_mmpbsa module

GROMACS version:2021
GROMACS modification: No
Hello. I want to calculate all energy parameters such as polar and nonpolar solvation energy in the G-mmpbsa module of gromacs for the desired protein by selecting protein as the first group and water as the second group. Is this method of calculating free energy for protein correct? Is it possible to calculate the free energy of a protein in a single form without a ligand, and if in the G-mmpbsa we select only one group with the incl_14 option and calculate all the energy parameters for one group, can the free energy of a protein be calculated?