Diagonalization of the Fock matrix

The Fock matrix is then diagonalized to yield the following set of eigenvalues, or one-electron energies, and eigenvectors, or molecular orbitals:

Energy Level	Molecular Orbital Coefficients
	1	2	3	4	5	6
6 -0.4857	0.4082	-0.4082	0.4082	-0.4082	0.4082	-0.4082
5 -1.8388	0.5774	-0.2887	-0.2887	0.5774	-0.2887	-0.2887
4 -1.8388	0.0000	0.5000	-0.5000	0.0000	0.5000	-0.5000
3 -6.9317	0.5774	0.2887	-0.2887	-0.5774	-0.2887	0.2887
2 -6.9317	0.0000	0.5000	0.5000	0.0000	-0.5000	-0.5000
1 -14.8670	0.4082	0.4082	0.4082	0.4082	0.4082	0.4082

These form a normalized, orthogonal set. Under the NDDO approximation, overlaps between different atomic orbitals are ignored, i.e., $<\varphi_i\vert\varphi_j>=\delta(i,j)$ , so instead of

$\begin{displaymath}<\psi_i\vert\psi_j> = \sum_{\lambda}\sum_{\sigma}c_{\lambda i}c_{\sigma j}<\varphi_{\lambda}\vert\varphi_{\sigma}> \end{displaymath}$

we have

$\begin{displaymath}<\psi_i\vert\psi_j> = \sum_{\lambda}c_{\lambda i}c_{\lambda j} = \delta(i,j). \end{displaymath}$