Restricted density functional response theory for open-shell systems

This work presents development, implementation and applications of density functional theory (DFT) methods for calculation molecular properties of open-shell molecules. The theory of restricted open-shell density functional response theory is briefly summarized and the advantages and disadvantages of a spin-restricted formulation is discussed. Sample calculations are presented and discussed for excitation energies, polarizabilities and ESR spectral parameters: g-tensors and A-tensors (hyperfine coupling constants). For the A-tensors a recent generalization of the restricted-unrestricted approach [Fernandez, et al., J. Chem. Phys. 97 (1992) 3412] has been used. It is found that the additional complexity of spin-restricted methods is motivated by the quality of our results.