Bloch's effective Hamiltonian is not Hermitian, which may not be convenient for the analysis. Des Cloizeaux gave a recipe for producing a Hermitian effective Hamiltonian by means of symmetric orthogonalization of Bloch's eigenvectors. An arbitrary Hermitian effective Hamiltonian can be obtained through Bloch's effective Hamiltonian through a similarity transformation A. For any Bloch's eigenprojector, this can be written as