Density functional calculations of molecular g-tensors in the zero-order regular approximation for relativistic effects

Abstract

A method has been developed for the calculation of the g-tensor of Kramers doublet open shell molecules, which uses the spinor of the unpaired electron of the paramagnetic molecule, obtained from a density functional calculation. Spin–orbit coupling is taken into account variationally using the zeroth-order regular approximation (ZORA) to the Dirac equation. The problem of gauge dependence is solved by using gauge including atomic orbitals (GIAO’s). The method gives fair agreement with experimental values for the g values of some small test molecules NO2, HCO, and TiF3.

A Nonorthogonal State-Interaction Approach for Matrix Product State Wave Functions

“…9,16-23 and literature citations in these works and in Refs. [8][9][10][11][13][14][15]. In these schemes, the calculation of a number of non-or scalar-relativistic many-particle spin-free states that are eigenfunctions of the spin-squared operator S 2 , is decoupled from a subsequent perturbative or variational mixing of the latter through the SO coupling operator to obtain SO coupled many-electron wave functions (e.g.…”

“…Similarly, calculating magnetic properties 6 such as molecular g-factors and electron-nucleus hyperfine coupling, which are central parameters in electron paramagnetic resonance (EPR) spectroscopy, requires spin-orbit coupled wave functions 7,8 . To this end, correlated two-and four-component ab initio wave function [9][10][11][12] , and density functional theory approaches [13][14][15] . In the present study we focus on EPR g-tensors for testing purposes, but it should be noted that the underlying novel method of gaining access to wave functions that include the effects from SOC has a vast range of applications.…”

The calculation of ESR parameters by density functional theory: the g- and A-tensors of Co(acacen)

“…Furthermore, with the recent developments to include relativistic effects in modern DFT calculations, spin-orbit (SO) coupling can be taken into account variationally using the zeroth-order regular approximation (ZORA) to the Dirac equation [5][6][7][8]. To obtain then the g-tensor, the effect of the external homogeneous magnetic field has only to be treated with first-order perturbation theory [9,10].…”

“…In this Letter, we present the result of calculations of the g-and A-tensors components for a transition metal complex: [Co(acacen)] or N,N 0 -ethylenebis(acetylacetoneiminato)cobalt(II), as obtained from two methods: (i) the ligand field -density functional theory (LFDFT) i.e., a method proposed by Atanasov et al [11,12] which is based on a DFT multi-determinants approach, (ii) directly, by calculating the Zeeman splitting of the ground Kramers doublet obtained by using ZORA calculation and second-order perturbation theory implemented in ADF for the hyperfine interaction [9,13]. The choice of this complex was motivated by two reasons: firstly, the [Co(acacen)] complex belongs to a series of complexes with tetradentate Schiff bases which received much attention during the last decades [14,15], largely because of their ability to reversibly absorb molecular oxygen under certain conditions.…”

Relativistic calculations of magnetic resonance parameters: background and some recent developments

“…One of them has been a new implementation of a method developed originally by van Lenthe et al [223] (LWA), which does not allow for spin polarization in the calculations. The second variant affords spin polarization.…”