The projection operator for a space spanned by a linearly dependent set
Manuel Berrondo, Per‐Olov Löwdin · International Journal of Quantum Chemistry · 1969
Abstract The explicit form of a projection operator constructed from a linearly dependent set is found. The relationships with canonical orthonormalization and with the cofactor matrix of the set's metric matrix are discussed. Similar expressions are obtained for the inner projection of a positive definite operator using a linearly dependent set.