On the efficiency of an effective Hamiltonian in spin-orbit CI calculations

Schimmelpfennig, Bernd; Maron, Laurent; Wahlgren, Ulf; Teichteil, Christian; Fagerli, Hilde; Gropen, Odd

doi:10.1016/s0009-2614(98)00120-1

Cited by 59 publications

(46 citation statements)

References 18 publications

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“…In order to put the various options into perspective, it is instructive to look at the calculated one-electron SOC constants of a number of first-row atoms ( Table 2): We note in passing that the popular atomic mean field SOC (AMFI) operator [106][107][108], that is used in popular program packages such as MOLCAS, is identical to the SOMF operator but makes two additional approximations: a) only one-center integrals are retained, b) the molecular density is replaced by a fixed atomic density. The AMFI operator hence does not respond to the molecular environment.…”

Section: Spin-orbit Couplingmentioning

confidence: 99%

First principles approach to the electronic structure, magnetic anisotropy and spin relaxation in mononuclear 3d-transition metal single molecule magnets

Atanasov

Aravena

Suturina

et al. 2015

Coordination Chemistry Reviews

318

367

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Section: Spin-orbit Couplingmentioning

confidence: 99%

First principles approach to the electronic structure, magnetic anisotropy and spin relaxation in mononuclear 3d-transition metal single molecule magnets

Atanasov

Aravena

Suturina

et al. 2015

Coordination Chemistry Reviews

318

367

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“…The SOMF approach has been developed by Hess et al 55 It is widely used within Schimmelpfennig's AMFI program in a number of quantum chemistry codes. 56,57 However, it introduces two further approximations which are (a) the neglect of multicenter SOC terms and (b) the use of atomic self-consistent field orbitals and their averaged occupation numbers in place of the molecular charge densities. Both approximations were introduced in the interest of computational efficiency and their justification is through the successful molecular test calculations.…”

Section: Theorymentioning

confidence: 99%

Calculation of Solvent Shifts on Electronic g-Tensors with the Conductor-Like Screening Model (COSMO) and Its Self-Consistent Generalization to Real Solvents (Direct COSMO-RS)

Sinnecker¹,

Rajendran²,

Klamt³

et al. 2006

J. Phys. Chem. A

564

496

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The conductor-like screening model (COSMO) was used to investigate the solvent influence on electronic g-values of organic radicals. The previously studied diphenyl nitric oxide and di-tert-butyl nitric oxide radicals were taken as test cases. The calculations employed spin-unrestricted density functional theory and the BP and B3LYP density functionals. The g-tensors were calculated as mixed second derivative properties with respect to the external magnetic field and the electron magnetic moment. The first-order response of the Kohn-Sham orbitals with respect to the external magnetic field was determined through the coupled-perturbed DFT approach. The spin-orbit coupling operator was treated using an accurate multicenter spin-orbit mean-field (SOMF) approach. Provided that important hydrogen bonds are explicitly modeled by a supermolecule approach and that the basis set is sufficiently saturated, the COSMO calculations lead to accurate predictions of isotropic g-shifts with deviations of not more than 100 ppm relative to experiment. Very accurate results were obtained by employing a recently developed self-consistent modification of the COSMO method to real solvents (COSMO-RS), which we briefly introduce in this paper as direct COSMO-RS (D-COSMO-RS). This model gives isotropic g-shifts of similar high accuracy for water without using the supermolecule approach. This is an important result because it solves many of the problems associated with the supermolecule approach such as local minima and the choice of a suitable model system. Thus, the self-consistent D-COSMO-RS incorporates some specific solvation effects into continuum models, in particular it appears to successfully model the effects of hydrogen bonding. Although not yet widely validated, this opens a novel approach for the calculation of properties which so far only could be calculated by the inclusion of explicit solvent molecules in continuum solvation methods.

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“…This problem can be handled by using an effective Hamiltonian where the diagonal matrix elements are shifted to reproduce large spin-free CI results. 22,23 In the effective Hamiltonian both orbital relaxation and dynamic correlation is mimicked by a simple shift in the diagonal matrix elements. The results of the spin-orbit calculations are presented in Table XII for CrF and in Table XIII for CrCl.…”

Section: Spin-orbit "So… Calculationsmentioning

confidence: 99%

“…Methods to treat scalar relativistic effects have been available for a decade, and lately efficient methods to compute spin-orbit effects have been developed. 2,3 Ab initio calculations can now be used as guidance when planning experiments or analyzing experimental results for quite complicated spectra. [4][5][6][7] In the present work, we deal mainly with information extracted from two different experiments.…”

Section: Introductionmentioning

confidence: 99%