Answer to the comment on "On the characteristic polynomial of an effective Hamiltonian''

In a recent comment by Fernández, it has been argued that our solution method of an effective Hamiltonian based on the characteristic polynomial [Phys. Lett. A 443 (2022) 128215] had been developed several years earlier by Fried and Ezra [J. Chem. Phys. 90 (1989) 6378]. We show here several important differences between our treatment and the resummation method proposed previously by Fried and Ezra.