A new scheme is presented for obtaining a pure spin state for the one-determinant wave function built on Hartree–Fock or Kohn–Sham orbitals. In this scheme, the unrestricted determinant is expanded in restricted determinants constructed in the basis set of spin-paired orbitals. Using spin projection, one can determine spin density components corresponding to pure spin states and estimate the weight of spin contaminants in the spin density. The efficiency of this approach is demonstrated on the example of methane oxidation. It is shown that self-consistent solutions of Hartree–Fock or Kohn–Sham equations with broken spin symmetry are not an artifact of one-determinant approximation. The equations reflect real spin polarization that creates negative spin density in some parts of the molecular system.
Предметные области OECD FOS+WOS
- 2.05 ТЕХНОЛОГИЯ МАТЕРИАЛОВ
- 1.04 ХИМИЧЕСКИЕ НАУКИ