= Orthogonal tight-binding approximation
In the <orthogonal tight-binding approximation>, localized basis states satisfy $\langle i|j\rangle=\delta_{ij}$ while the <Hamiltonian> retains nonzero <hopping integrals>. These are independent matrix elements: orthogonal states need not have vanishing Hamiltonian coupling. One can construct localized orthonormal orbitals from overlapping atomic orbitals; truncating the resulting Hamiltonian to nearest neighbours is a further approximation. An overlap matrix must instead be retained for raw nonorthogonal orbitals.
Back to article page
