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UHF

Description

The spin-unrestricted Hartree-Fock method will be used. This requires that each electron is treated separately rather than as a spin-matched pair. UHF should be used for open-shell systems. For closed-shell systems, the UHF solution will collapse to the RHF solution if the RHF description is of sufficient flexibility. Caution should be exercised in the use of UHF as it will generally require more computational effort than RHF for those systems to which RHF is suited.