Multi-configurational short-range density functional theory can describe spin–spin coupling constants of transition metal complexes

Abstract

The multi-configurational short-range density functional theory (MC-srDFT) has been extended to the calculation of indirect spin-spin coupling constants (SSCCs) for NMR spectroscopy. The performance of the new method is compared to Kohn-Sham density functional theory (KS-DFT) and ab initio CASSCF for a selected set of molecules with good reference values. Two families of density functionals are considered, the local density approximation (sr)LDA and the generalized gradient approximation (sr)PBE. All srDFT calculations are of Hartree-Fock type or complete active space type, HF-srDFT or CAS-srDFT. In all cases the calculated SSCC values are of the same quality for srLDA and srPBE functionals, suggesting one should use the computationally cheaper srLDA functionals in applications. For all calculated SSCCs in organic compounds the best choice is HF-srDFT, the more expensive CAS-srDFT does not provide better values for these single-reference molecules. Fluorine is a challenge, in particular FF, FC and FO couplings have much higher statistical errors than the rest. For SSCCs involving fluorine and a metal atom CAS-srDFT with singlet gTDA is needed to get good SSCC values although the reference ground state is not a multi-reference case. For VF −1 6 all other considered models fail blatantly.

Perspective: multi-configurational methods in bio-inorganic chemistry

“…Based on analysis of small model systems a value of m = 0.4 was previously suggested as this allocated the largest possible portion of dynamical correlation at the DFT functional. 87 This value was also optimal for excitation energies of organic systems, [90][91][92][93] but exploration of transition metal complexes have later shown that both m = 0.4 [94][95][96] and larger values 97 can yield accurate results.…”

DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science

“…[499][500][501] Preliminary investigations of transition-metal complexes indicate that a value around = 1.0 may be needed to describe their spin correlation sufficiently well. 502 A particularly promising choice for the lrWFT part is to use the variational multiconfigurational self-consistent field description, leading to an lrMCSCF-srDFT (MC-srDFT) model. Because it is variational, the MC-srDFT model can also be used for molecular response properties, just like TDDFT in Kohn-Sham DFT -not only for excitation energies and transition moments, but in general for optical, electrical, and magnetic perturbations.…”

“…499–501 Preliminary investigations of transition-metal complexes indicate that a value around μ = 1.0 may be needed to describe their spin correlation sufficiently well. 502…”

DFT Exchange: Sharing Perspectives on the Workhorse of Quantum Chemistry and Materials Science

“…[499][500][501] Preliminary investigations of transition-metal complexes indicate that a value around µ = 1.0 may be needed to describe their spin correlation sufficiently well. 502 A particularly promising choice for the lrWFT part is to use the variational multiconfigurational self-consistent field description, leading to an lrMCSCF-srDFT (MC-srDFT) model. Because it is variational, the MC-srDFT model can also be used for molecular response properties, just like TDDFT in Kohn-Sham DFTnot only for excitation energies and transition moments, but in general for optical, electrical, and magnetic perturbations.…”