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Open access

Michal Malček, Lukáš Bučinský and Stanislav Biskupič

Calculations of hyperfine coupling constant of the TMPD molecule

The calculations of the hyperfine coupling constants (HFCC) of tetramethyl-p-Phenylenediamine (TMPD) are presented. Several DFT functionals are employed and the results are compared with the UHF and MP2 level of theory. Sensitivity of HFCC to the choice of the basis set is investigated. Impact of the different conformers of TMPD and the equivalence of methyl group hydrogens on the HFCC values is considered. The solvent effects are introduced via polarizable continuum model and compared with in vacuo calculations. Last but not least, molecular dynamics is employed to include the solvent molecules as well as the dynamics explicitly, accounting similar conditions comparing to the liquid phase EPR experiment.

Open access

Michal Malček, Lukáš Bučinský and Stanislav Biskupič

Abstract

Sensitivity of contact spin density as well as electron density to the size of nucleus is investigated using the Gaussian model of nucleus and the point charge nucleus model. Scalar Infinite Order Two Component and scalar second order Douglas-Kroll-Hess quasirelativistic contact spin densities (spin densities at the nucleus) of Cu, Ag and Au atoms are considered. The non-relativistic contact spin densities and the valence s-orbital contact densities of Kramers restricted orbitals (Cu, Ag, Au atoms) are presented as well. The picture change error in the quasirelativistic calculations of spin densities is corrected by analytic means. Uncontracted triple-zeta UTZ+Ns basis sets are employed, where N is the number of additional tight s Gaussians. In addition, the impact of tight p and d Gaussians is briefly discussed.