Bofill89

J. M. Bofill and P. Pulay, “The unrestricted natural orbital-complete active space (UNO-CAS) method: An inexpensive alternative to the complete active space-self-consistent-field (CAS-SCF) method,” J. Chem. Phys., 90 (1989) 3637-46. DOI: 10.1063/1.455822