TY - JOUR
T1 - Transmission of spin-polarization by π-orbitals
T2 - an approach to assessing its effect on NMR spin-spin coupling and EPR hyperfine structure
AU - Malkina, Olga L.
AU - Lemken, Florian
AU - Asher, James R.
AU - Hierso, Jean-Cyrille
AU - Buehl, Michael
AU - Malkin, Vladimir G.
N1 - Funding: We acknowledge the support from Slovak-French PHC Stefanik project “Spin Coupling Advanced Level Perception” (SCALP). OM, VM and JRA acknowledge the support from Slovak grant agencies APVV (grants No. SK-FR-19-0001 and APVV-19-0516) and VEGA (grant No. 2/0135/21). This work was also supported
by the CNRS, the Université de Bourgogne, the Conseil Régional BFC (CHIMENE project), the PIA-excellence ISITE-BFC program (COMICS project) and the FEDER, which are all sincerely thanked.
PY - 2022/9/27
Y1 - 2022/9/27
N2 - A new approach to assessing the effect of the transmission of
spin-polarization by π-orbitals (π-TSP) is presented. In order to switch
off the π-TSP effect, we artificially average the α- and β-densities of
the valence π-orbitals when calculating the exchange–correlation
contribution to the Fock matrix in the unrestricted Kohn–Sham framework.
The π-TSP effect is then evaluated as the difference between the
results obtained with switched-on and switched-off options. This
approach is applied to estimate the π-TSP effect on the Fermi-contact
contribution to spin–spin couplings and EPR hyperfine structure coupling
constants. The π-TSP effect on the distribution of spin-density,
spin–spin coupling pathways and pathways of EPR hyperfine couplings is
demonstrated for benzene, naphthalene, 1,3,5,7,9-decapentaene and the
1,3,5,7,9-decapentaen-1-yl radical. The sign alternation of the
spin-polarization transmitted by π-orbitals is explained in a
theoretical framework based on perturbation theory. However, the
delocalized nature of the π-system can interfere with the sign
alternation in certain cases, two of which – the cyclobutadiene dication
and the cyclooctatetraene dication – are examined, and an explanation
for which is provided.
AB - A new approach to assessing the effect of the transmission of
spin-polarization by π-orbitals (π-TSP) is presented. In order to switch
off the π-TSP effect, we artificially average the α- and β-densities of
the valence π-orbitals when calculating the exchange–correlation
contribution to the Fock matrix in the unrestricted Kohn–Sham framework.
The π-TSP effect is then evaluated as the difference between the
results obtained with switched-on and switched-off options. This
approach is applied to estimate the π-TSP effect on the Fermi-contact
contribution to spin–spin couplings and EPR hyperfine structure coupling
constants. The π-TSP effect on the distribution of spin-density,
spin–spin coupling pathways and pathways of EPR hyperfine couplings is
demonstrated for benzene, naphthalene, 1,3,5,7,9-decapentaene and the
1,3,5,7,9-decapentaen-1-yl radical. The sign alternation of the
spin-polarization transmitted by π-orbitals is explained in a
theoretical framework based on perturbation theory. However, the
delocalized nature of the π-system can interfere with the sign
alternation in certain cases, two of which – the cyclobutadiene dication
and the cyclooctatetraene dication – are examined, and an explanation
for which is provided.
U2 - 10.1039/D2CP03295C
DO - 10.1039/D2CP03295C
M3 - Article
SN - 1463-9076
VL - Advance Article
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
ER -