Spin-Projected Divide-and-Conquer Unrestricted Self-Consistent Field: Practical Linear-Scaling Approaches for Static Correlation.
The spin-unrestricted Hartree-Fock (UHF) method effectively accounts for static electron correlation, albeit at the expense of broken spin symmetry in the wavefunction. Such broken-symmetry UHF solutions suffer from spin contamination, which degrades the accuracy of molecular properties and excited-state calculations....