On the hybridization problem in H2O by Hückel transformation theory

An orthogonal transformation of the oxygen valence AOs belonging to A1 symmetry to an ω-hybridized sp basis set allows for useful simplifications reducing Hückel transformed matrix for ground state H2O to nearly block-diagonal form. Neglecting delocalization of the hybrid lone pair into the bond, minimization of the resulting Hückel energy shows that for ω ≠ 0 the interbond angle opens beyond 90°. A further orthogonal transformation involving the B2 y AO yields three orthogonal sp2 hybrids of C2v symmetry on oxygen which can be engaged in two equivalent straight O–H bonds making the experimental interbond angle and locally minimizing the Hückel energy of the valence electron configuration.