Chapter 15. External Electromagnetic Fields and Molecular Properties

  1. Prof. Dr. Markus Reiher and
  2. Dr. Alexander Wolf

Published Online: 22 JUN 2009

DOI: 10.1002/9783527627486.ch15

Relativistic Quantum Chemistry: The Fundamental Theory of Molecular Science

Relativistic Quantum Chemistry: The Fundamental Theory of Molecular Science

How to Cite

Reiher, M. and Wolf, A. (2009) External Electromagnetic Fields and Molecular Properties, in Relativistic Quantum Chemistry: The Fundamental Theory of Molecular Science, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi: 10.1002/9783527627486.ch15

Author Information

  1. ETH Zuerich, Laboratory for Physical Chemistry, Hoenggerberg Campus, Wolfgang-Pauli-Strasse 10, 8093 Zuerich, Switzerland

Publication History

  1. Published Online: 22 JUN 2009
  2. Published Print: 14 JAN 2009

ISBN Information

Print ISBN: 9783527312924

Online ISBN: 9783527627486

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Keywords:

  • external electromagnetic fields;
  • molecular properties;
  • four-component perturbation;
  • response theory;
  • two-component form;
  • picture change artifacts;
  • Douglas–Kroll–Hess property transformation;
  • magnetic fields in resonance spectroscopies;
  • electric field gradient;
  • nuclear quadrupole moment;
  • parity violation;
  • electro-weak chemistry

Summary

The relativistic calculation of observables and molecular properties follows the lines elaborated first in nonrelativistic quantum chemistry, in which the small electromagnetic perturbation is considered in a Taylor expansion of the electronic energy. Molecular properties are then defined as the derivatives in this expansion. However, the relativistic minimal coupling principle allows for a rigorous inclusion of electromagnetic fields. Thus, four-component theory of response properties derived from this perturbation is naturally a consistent framework. Such a theory, however, requires the perturbed wave function, which is usually expanded in terms of the set of eigenfunctions of the unperturbed Hamiltonian so that the role of the negative-energy states has to be clarified. In particular, they become decisive for the explanation of the diamagnetic contribution of magnetic-response parameters. Again, two-component schemes are free of negative-energy states, but this benefit needs to be analyzed carefully. Also, they suffer from the so-called picture-change error.