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Density Functional Theory for EPR and NMR Spin Hamiltonian Parameters
KTH, Superseded Departments, Biotechnology.ORCID iD: 0000-0003-2729-0290
2004 (English)Doctoral thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH , 2004. , v, 51 p.
Keyword [en]
DFT, EPR, NMR, response theory
National Category
Theoretical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-3760ISBN: 91-7283-748-9 (print)OAI: oai:DiVA.org:kth-3760DiVA: diva2:9610
Public defence
2004-05-27, 00:00
Note
QC 20100622Available from: 2004-05-26 Created: 2004-05-26 Last updated: 2011-09-16Bibliographically approved
List of papers
1. Calculations of nuclear magnetic shielding in paramagnetic molecules
Open this publication in new window or tab >>Calculations of nuclear magnetic shielding in paramagnetic molecules
2003 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 118, no 6, 2550-2561 p.Article in journal (Refereed) Published
Abstract [en]

We propose and evaluate first principles methods for calculating the nuclear shielding tensor in open-shell, paramagnetic molecules, dealing with the case of small spin-orbit coupling that, in turn, implies the best applicability to light, organic compounds. The formalism is consistent up to second order in the fine structure constant, and includes orbital, fully anisotropic dipolar, and isotropic contact contributions to the tensor. The proposed method is implemented within the ab initio single- and multiconfiguration self-consistent field as well as density functional theory frameworks. The applications include small main-group radicals and larger nitroxide radicals. The analysis of the results and comparison with the experimental nuclear magnetic resonance data, which are available for the latter compounds, indicate promising accuracy and applicability of the density functional theory method to chemically interesting problems.

Keyword
HYPERFINE COUPLING-CONSTANTS, DENSITY-FUNCTIONAL CALCULATIONS, GENERALIZED GRADIENT APPROXIMATION, CONSISTENT-FIELD CALCULATIONS, SPIN-ORBIT PSEUDOPOTENTIALS, INHOMOGENEOUS ELECTRON-GAS, CORRELATION-ENERGY, EXCHANGE-ENERGY, WAVE-FUNCTIONS, RADICALS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-13644 (URN)10.1063/1.1535904 (DOI)000180564800012 ()
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-22 Last updated: 2010-09-23Bibliographically approved
2. Restricted density functional theory of linear time-dependent properties in open-shell molecules
Open this publication in new window or tab >>Restricted density functional theory of linear time-dependent properties in open-shell molecules
Show others...
2003 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 1, 34-46 p.Article in journal (Refereed) Published
Abstract [en]

In this paper we report the derivation and the performance of a spin-restricted density functional formalism for linear time-dependent properties in open-shell molecules. The formalism is based on an exponential parameterization of the density operator with the response functions defined through Ehrenfest's principle. In addition to the derivation of formulas, details of implementation are given as well as a discussion of numerical results for excitation energies and dynamic polarizabilities for a selected set of radicals.

Keyword
ELECTRONIC ABSORPTION-SPECTRA, HYDROCARBON RADICAL CATIONS, EXCITATION-ENERGIES, RESPONSE THEORY, LOCAL-DENSITY, CONJUGATED MOLECULES, EXCITED-STATES, BASIS-SETS, APPROXIMATION, POLARIZABILITIES
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-13643 (URN)10.1063/1.1577329 (DOI)000183585400006 ()
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-22 Last updated: 2011-12-15Bibliographically approved
3. Restricted density-functional linear response theory calculations of electronic g-tensors
Open this publication in new window or tab >>Restricted density-functional linear response theory calculations of electronic g-tensors
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2003 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 20, 10489-10496 p.Article in journal (Refereed) Published
Abstract [en]

A method for calculations of electronic g-tensors based on a spin-restricted open-shell Kohn-Sham formalism and linear response theory is described. Test calculations for main group organic radicals and transition metal compounds have been carried out using two different spin-orbit approximations: Scaled spin-orbit and atomic mean-field spin-orbit operators. The results indicate slightly better performance of the proposed spin-restricted approach compared to previous methods based on the unrestricted Kohn-Sham formalism. An exception to this general improvement are the anions, as they show considerable spin-polarization. The results also show the superiority of the atomic mean field spin-orbit approximation of the spin-orbit operator with respect to the scaled approximation. For main group radicals, quantitative agreement with high level ab initio as well as experimental data are achieved, whereas for transition metal compounds the results systematically underestimate experimental values, showing also a considerable dependency on the employed exchange correlation functional, similarly to previous reports on calculations using unrestricted density functional theory. From this work we conclude that these problems are not primarily associated with the spin-contamination problem, and that they must be referred to the current time-dependent density functional theories as such.

Keyword
EFFECTIVE NUCLEAR CHARGES, SPIN-ORBIT CALCULATIONS, CORRELATION-ENERGY, HARTREE-FOCK, APPROXIMATION, EXCHANGE, OPERATORS, MOLECULES, ACCURATE, GAS
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-13642 (URN)10.1063/1.1620497 (DOI)000186554500004 ()
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-22 Last updated: 2010-09-23Bibliographically approved
4. Density functional theory of nonlinear triplet response properties with applications to phosphorescence
Open this publication in new window or tab >>Density functional theory of nonlinear triplet response properties with applications to phosphorescence
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2003 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 21, 11024-11034 p.Article in journal (Refereed) Published
Abstract [en]

We present density functional response theory generalized to triplet excitations. A method based on an exponential parametrization of the spin-dependent density operator is derived for the evaluation of linear and quadratic response functions for spin-dependent perturbations. The developed methodology is applicable to commonly available functionals, also hybrid functionals including exchange-correlation functionals at the general gradient-approximation level and fractional exact Hartree-Fock exchange. Illustrative calculations are presented for singlet-triplet transition moments and phosphorescence lifetimes, providing numerical data on these quantities for the first time using time-dependent density functional theory.

Keyword
molecular-orbital methods, correct asymptotic-behavior, correlated wave-functions, gaussian-basis sets, mean-field, exchange, state, atoms, formaldehyde, lifetime
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-13728 (URN)10.1063/1.1622926 (DOI)000186492900005 ()
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-24 Last updated: 2011-12-15Bibliographically approved
5. Influence of hydrogen bonding in the paramagnetic NMR shieldings of nitronylnitroxide derivative molecules
Open this publication in new window or tab >>Influence of hydrogen bonding in the paramagnetic NMR shieldings of nitronylnitroxide derivative molecules
2004 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 4, 1197-1206 p.Article in journal (Refereed) Published
Abstract [en]

We apply our recently developed methodology for first-principles computations of paramagnetic NMR shieldings and explore the shieldings in a selected set of radicals that form core units in molecular magnets. The influence on these parameters of hydrogen bonding, that corresponds to the crystal environment, is the prime objective of the study. Nitronylnitroxide radicals with the hydroxyphenyl group in the ortho, meta, and para positions, as well as p-methoxyphenyl derivatives, are chosen for this purpose. The strong (NOHO)-H-... hydrogen bonding in the real crystal structure has been simulated by adding water molecules in the twelve molecular complexes investigated. Comparison of calculated and experimental data is made by taking the special features of the solid state and solution environments into account. The observed change in the shielding constant due to hydrogen bonding is explained by the spin delocalization picture; the dominating contribution is the temperature-dependent contact shielding containing the isotropic hyperfine coupling constant.

Keyword
NITRONYL NITROXIDE RADICALS, POLARIZED NEUTRON-DIFFRACTION, SPIN-ORBIT PSEUDOPOTENTIALS, DENSITY-FUNCTIONAL THEORY, AB-INITIO, FERROMAGNETIC INTERACTIONS, ORGANIC FERROMAGNET, MAGNETIC-PROPERTIES, AMINOXYL RADICALS, CRYSTAL PACKING
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-13641 (URN)10.1021/jp030693g (DOI)000188535700008 ()2-s2.0-0442295459 (Scopus ID)
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-22 Last updated: 2011-10-31Bibliographically approved
6. Electronic g-tensors of solvated molecules using the polarizable continuum model
Open this publication in new window or tab >>Electronic g-tensors of solvated molecules using the polarizable continuum model
2004 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, 5051- p.Article in journal (Refereed) Published
Abstract [en]

We present the implementation of density functional response theory combined with the polarizable continuum model (PCM), enabling first principles calculations of molecular g-tensors of solvated molecules. The calculated g-tensor shifts are compared with experimental g-tensor shifts obtained from electron paramagnetic resonance spectra for a few solvated species. The results indicate qualitative agreement between the calculations and the experimental data for aprotic solvents, whereas PCM fails to reproduce the electronic g-tensor behavior for protic solvents. This failure of PCM for protic solvents can be resolved by including into the model those solvent molecules which are involved in hydrogen bonding with the solute. The results for the protic solvents show that the explicit inclusion of the solvent molecules of the first solvation sphere is not sufficient in order to reproduce the behavior of the electronic g-tensor in protic solvents, and that better agreement with experimental data can be obtained by including the long-range electrostatic effects accounted for by the PCM approach on top of the explicit hydrogen-bonded complexes.

Keyword
hyperfine coupling-constants, density-functional calculations, semiquinone radical-anions, nitroxide spin-label, nitric oxide, correlation-energy, orbit operators, linear-response, epr parameters, hartree-fock
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-6174 (URN)10.1063/1.1779568 (DOI)000223720600005 ()2-s2.0-4944231543 (Scopus ID)
Note
QC 20100923 QC 20110916Available from: 2006-09-22 Created: 2006-09-22 Last updated: 2012-03-21Bibliographically approved
7. Density functional theory for hyperfine coupling constants with the restricted-unrestricted approach
Open this publication in new window or tab >>Density functional theory for hyperfine coupling constants with the restricted-unrestricted approach
2004 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 16, 7614-7623 p.Article in journal (Refereed) Published
Abstract [en]

This work presents derivation, implementation, and the first applications of the restricted-unrestricted approach based on restricted Kohn-Sham formalism for evaluation of hyperfine coupling constants. By using the spin-restricted Kohn-Sham method the well-known spin contamination problem existing in the unrestricted Kohn-Sham formalism is avoided and a proper description of spin polarization is achieved via the restricted-unrestricted approach without introducing spin contamination into the evaluation of the hyperfine coupling constants. The performance of the proposed formalism is evaluated for a set of organic radicals and transition metal compounds. The results of this investigation indicate promising accuracy of the restricted-unrestricted approach for calculation of the isotropic hyperfine coupling constants in organic radicals as well as transition metal compounds.

Keyword
TRANSITION-METAL-COMPLEXES, RADICALS, EPR
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-13639 (URN)10.1063/1.1799013 (DOI)000224456500011 ()2-s2.0-8344231616 (Scopus ID)
Note
QC 20100624Available from: 2010-06-24 Created: 2010-06-22 Last updated: 2010-09-23Bibliographically approved
8. Relativistic nuclear shieldings obtained by linear and quadratic density functional response theory
Open this publication in new window or tab >>Relativistic nuclear shieldings obtained by linear and quadratic density functional response theory
(English)Manuscript (Other academic)
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-5750 (URN)
Note
QC 20100624Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2011-02-04Bibliographically approved

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  • nn-NO
  • nn-NB
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  • Other locale
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Output format
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