Orthogonalization of fermion k -body operators and representability

  title={Orthogonalization of fermion 
-body operators and representability},
  author={Volker Bach and Robert Rauch},
  journal={Physical Review A},
The reduced k-particle density matrix of a density matrix on finite-dimensional, fermion Fock space can be defined as the image under the orthogonal projection in the Hilbert-Schmidt geometry onto the space of k-body observables. A proper understanding of this projection is therefore intimately related to the representability problem, a long-standing open problem in computational quantum chemistry. Given an orthonormal basis in the finite-dimensional one-particle Hilbert space, we explicitly… 
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