The canonical orthogonalization of AO basis set and block diagonalization of the hamiltonian matrix

On the basis of a general conclusion expressed in the Appendix, in this paper, we firstly discuss the symmetry properties of the orthogonalized AO basis set obtained by use of the canonical orthogonalization, then suggest a simple and systematic method for constructing a set of ortho-normalized symmetry orbitais which are fully classified according to the basis vectors for the rows of the irreducible representations of the corresponding molecular point symmetry group. By use of the orbitais obtained, the Hamiltonian or Fock matrix can be fully block diagonalized according to the rows of the irreducible representations.