The ambiguity of the atomic magnetization

Châtel, P.F. de; Ayuel, K.

doi:10.1016/s0921-4526(99)00044-7

Cited by 6 publications

(8 citation statements)

References 5 publications

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“…Any curlfree vector field can be added to M (x) without changing this information, fact which has been referred to as "gauge freedom" of the magnetization in Refs. [56][57][58]. A careful examination of the procedure described in Ref.…”

Section: )mentioning

confidence: 99%

Functional approach to electrodynamics of media

Starke

Schober

2015

Photonics and Nanostructures - Fundamentals and Applications

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In this article, we put forward a new approach to electrodynamics of materials. Based on the identification of induced electromagnetic fields as the microscopic counterparts of polarization and magnetization, we systematically employ the mutual functional dependencies of induced, external and total field quantities. This allows for a unified, relativistic description of the electromagnetic response without assuming the material to be composed of electric or magnetic dipoles. Using this approach, we derive universal (material-independent) relations between electromagnetic response functions such as the dielectric tensor, the magnetic susceptibility and the microscopic conductivity tensor. Our formulae can be reduced to well-known identities in special cases, but more generally include the effects of inhomogeneity, anisotropy, magnetoelectric coupling and relativistic retardation. If combined with the Kubo formalism, they would also lend themselves to the ab initio calculation of all linear electromagnetic response functions.

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Section: )mentioning

confidence: 99%

Functional approach to electrodynamics of media

Starke

Schober

2015

Photonics and Nanostructures - Fundamentals and Applications

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“…One may at this point ask whether the spin density purportedly obtained by experiment corresponds to these definitions. Critical studies 36, 37 point out that in an inelastic neutron scattering experiment the neutron beam “sees” the current density rather than the spin density of the sample and one has to separate the orbital and spin contributions of this quantity. Furthermore, the nonrelativistic definition of the current density contains the curl of the spin density which means that only the transverse part of the spin density can be extracted, leaving gauge freedom for the longitudinal part.…”

Section: Introductionmentioning

confidence: 99%

Relativistic adiabatic time‐dependent density functional theory using hybrid functionals and noncollinear spin magnetization

Bast

Jensen

Saue

2009

Int J of Quantum Chemistry

132

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ABSTRACT:We report an implementation of adiabatic time-dependent density functional theory based on the 4-component relativistic Dirac-Coulomb Hamiltonian and a closed-shell reference. The implementation includes noncollinear spin magnetization and full derivatives of functionals, including hybrid generalized gradient approximation (GGA) functionals. We avoid reducing the generalized eigenvalue problem to half the dimension involving the square of excitation energies since this may introduce spurious roots and also squares the matrix condition number. Rather we impose structure in terms of hermiticity and time reversal symmetry on trial vectors to obtain even better reductions in terms of memory and run time, and without invoking approximations. BAST, JENSEN, AND SAUE symmetry scheme where symmetry reductions translate into reduction of algebra from quaternion to complex or real. For hybrid GGAs with noncollinear spin magnetization we derive a new computationally advantageous equation for the full second variational derivatives of such exchange-correlation functionals. We apply our implementation to calculations on the ns 2 → ns 1 np 1 excitation energies in the Zn, Cd, and Hg atoms (n = 4-6) and (vertical) excitation energies of UO 2+ 2 ; and we test the performance of various functionals by comparison with experimental data (group 12 atoms) or higher-level computational results (UO 2+ 2 ). The results indicate that the adiabatic local density approximation (ALDA) is a good approximation for some GGA functionals, but not all. Furthermore, the results also indicate that ALDA is an extremely bad approximation for hybrid functionals, unless one only employs ALDA for the pure DFT contribution to the exchange-correlation kernel and retains the fraction of exact exchange; we denote this approximation ALDAh.

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“…(i) Gauge freedom of the polarizations? References [40,68,[80][81][82][83] stipulate a "gauge freedom" in the definition of {P , D} and {M , H}, meaning that the transverse and respectively longitudinal parts of these pairs can be arbitrarily altered, while only the respective sums,…”

Section: Incomplete Field Equationsmentioning

confidence: 99%

Ab initio materials physics and microscopic electrodynamics of media

Starke¹,

Schober²

2016

Preprint

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We argue that the amazing progress of first-principles materials physics necessitates a revision of the Standard Approach to electrodynamics of media. We hence subject this Standard Approach to a thorough critique, which shows both its inherent conceptual problems and its practical inapplicability to modern ab initio calculations. We then go on to show that the common practice in ab initio materials physics has overcome these difficulties by taking a different, microscopic approach to electrodynamics of media, only superficially resembling the Standard Approach whose validity is restricted to the macroscopic domain. As this paradigm shift went largely unnoticed outside and partly even within the ab initio community, the present article aims at a systematic development and paradigmatic discussion of this new, microscopic first-principles approach to electrodynamics of media, for which we propose the name Functional Approach.

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The ambiguity of the atomic magnetization

Cited by 6 publications

References 5 publications

Functional approach to electrodynamics of media

Functional approach to electrodynamics of media

Relativistic adiabatic time‐dependent density functional theory using hybrid functionals and noncollinear spin magnetization

Ab initio materials physics and microscopic electrodynamics of media

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