Topic
Symmetry (physics)
About: Symmetry (physics) is a research topic. Over the lifetime, 26435 publications have been published within this topic receiving 500189 citations. The topic is also known as: symmetry (physics) & physical symmetry.
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TL;DR: In this paper, the authors considered dislocations of edge type with an infinite straight line as axis, but apply to a material with the symmetry of any of the crystal classes, where the axis of the dislocation may be arbitrarily inclined to the symmetry axes of the material.
Abstract: Burgers has discussed dislocations in materials with cubic symmetry for the general case in which the dislocation axis is an arbitrary curve. The results of the present paper are limited to dislocations of edge type with an infinite straight line as axis, but apply to a material with the symmetry of any of the crystal classes. The axis of the dislocation may be arbitrarily inclined to the symmetry axes of the material. Expressions are given for the elastic displacements and the energy of the dislocation. Nabarro's calculation of the width of a dislocation is extended to the anisotropic case.
256 citations
TL;DR: In this article, the dual symmetry of the non-linear σ model has been analyzed and shown to exist if and only if the field takes values in a symmetric space.
255 citations
TL;DR: In this article, the full symmetry groups for all single-wall and multi-wall carbon nanotubes are found, and the optical activity is studied within this framework, and a detailed classification of the possible nanotube-based optical devices is given.
Abstract: The full symmetry groups for all single-wall and multiwall carbon nanotubes are found. As for the single-wall tubes, the symmetries form non-Abelian nonsymorphic line groups, enlarging the groups reported in the literature. In the multiwall case, any type of line and axial point groups can be obtained, depending on single-wall constituents and their relative position. The isogonal symmetry is related to the macroscopic tensor properties of the nanotubes. The optical activity is studied within this framework, and a detailed classification of the possible nanotube-based optical devices is given. At the microscopic level, full symmetry is used to find general forms of the characteristic functions of the nanotubes. In particular, the stability of the double-wall configurations and the possibility of chiral currents are discussed. Several other consequences are discussed: quantum numbers and related selection rules, phonon spectra, etc. In particular, the bands of the zigzag and the armchair tubes are generally expected to be fourfold degenerate.
255 citations
TL;DR: In this paper, the relations among polarimetric backscattering coefficients from the viewpoint of symmetry groups are analyzed for both reciprocal and non-reciprocal cases, and the properties derived under these transformations are general and apply to all scattering mechanisms in a given symmetrical configuration.
Abstract: This paper presents the relations among polarimetric backscattering coefficients from the viewpoint of symmetry groups. Symmetry of geophysical media encountered in remote sensing due to reflection, rotation, azimuthal, and centrical symmetry groups is considered for both reciprocal and nonreciprocal cases. On the basis of the invariance under symmetry transformations in the linear polarization basis, the scattering coefficients are related by a set of equations which restrict the number of independent parameters in the polarimetric covariance matrix. The properties derived under these transformations are general and apply to all scattering mechanisms in a given symmetrical configuration. The scattering coefficients calculated from theoretical models for layer random media and rough surfaces are shown to obey the derived symmetry relations. Use of symmetry properties in remote sensing of structural and environmental responses of scattering media is discussed. As a practical application, the results from this paper provide new methods for the external calibration of polarimetric radars without the deployment of man-made calibration targets.
254 citations
TL;DR: In this article, an effective potential is presented which matches S, P, and D-wave nucleon-nucleon phase parameters up to 320 MeV without generating the usual strong, short-range correlations.
254 citations