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  • Antisymmetry: Fundamentals and Applications
    Annual Review of Materials Research, 2020
    Co-Authors: Hari Padmanabhan, Jason M. Munro, Ismaila Dabo, Venkatraman Gopalan
    Abstract:

    Symmetry is fundamental to understanding our physical world. An Antisymmetry operation switches between two different states of a trait, such as two time-states, position-states, charge-states, spin-states, chemical-species etc. This review covers the fundamental concepts of Antisymmetry, and focuses on four antisymmetries, namely spatial inversion in point groups, time reversal, distortion reversal and wedge reversion. The distinction between classical and quantum mechanical descriptions of time reversal is presented. Applications of these antisymmetries in crystallography, diffraction, determining the form of property tensors, classifying distortion pathways in transition state theory, finding minimum energy pathways, diffusion, magnetic structures and properties, ferroelectric and multiferroic switching, classifying physical properties in arbitrary dimensions, and Antisymmetry-protected topological phenomena are presented.

  • Antisymmetry fundamentals and applications
    Annual Review of Materials Research, 2020
    Co-Authors: Hari Padmanabhan, Jason M. Munro, Ismaila Dabo, Venkatraman Gopalan
    Abstract:

    Symmetry is fundamental to understanding our physical world. An Antisymmetry operation switches between two different states of a trait, such as two time states, position states, charge states, spi...

  • The Antisymmetry of distortions
    Nature communications, 2015
    Co-Authors: Brian K. Vanleeuwen, Venkatraman Gopalan
    Abstract:

    Distortions are ubiquitous in nature. Under perturbations such as stresses, fields or other changes, a physical system reconfigures by following a path from one state to another; this path, often a collection of atomic trajectories, describes a distortion. Here we introduce an Antisymmetry operation called distortion reversal that reverses a distortion pathway. The symmetry of a distortion pathway is then uniquely defined by a distortion group; it has the same form as a magnetic group that involves time reversal. Given its isomorphism to magnetic groups, distortion groups could have a commensurate impact in the study of distortions, as the magnetic groups have had in the study of magnetic structures. Distortion symmetry has important implications for a range of phenomena such as structural and electronic phase transitions, diffusion, molecular conformational changes, vibrations, reaction pathways and interface dynamics.

  • The 17,803 types of double Antisymmetry space groups
    Acta Crystallographica Section A Foundations and Advances, 2014
    Co-Authors: Brian K. Vanleeuwen, Mantao Huang, Daniel B. Litvin, Venkatraman Gopalan
    Abstract:

    "Double Antisymmetry, as a type of color symmetry, refers to the consideration of two independent color-reversing operations. We found that there are 17,803 types of double Antisymmetry space groups. The ""types"" of double Antisymmetry space groups being the proper affine equivalence classes thereof, i.e. if two groups differ only by changes in origin, lattice constants, and angles then they are considered the same type of group, just as with the 230 types of crystallographic space groups. The significance of listing the types of double Antisymmetry space groups is that it gives all possible symmetries of a crystal when two independent antisymmetries are considered in conjunction with the conventional 3D Euclidean space symmetry. Examples from our listing of their properties and symmetry diagrams (available online) will be given."

  • Double Antisymmetry in magnetic structures
    Acta Crystallographica Section A Foundations and Advances, 2014
    Co-Authors: Brian K. Vanleeuwen, Mantao Huang, Daniel B. Litvin, Venkatraman Gopalan
    Abstract:

    This work follows from the recent introduction of the rotation-reversal operation intended to be analogous to the time-reversal operation used to describe the symmetry of magnetic structures. As a second independent Antisymmetry operation, this operation "doubles" the Antisymmetry of the magnetic space groups, hence the term double Antisymmetry. Supposing the consideration of both rotation-reversal and time-reversal symmetry, it was found that there are 17,803 types of symmetry that a crystal could exhibit; the 1,651 magnetic space group types being a subset of these, just as the 230 crystallographic space group types are a subset of the magnetic space group types. In addition to discussing the methods applied to determine these types, describing their properties, and listing their symmetry diagrams (available online), the implications for symmetry constraints in magnetic structure determination will be explored.

Vladimir S Manko - One of the best experts on this subject based on the ideXlab platform.

Phan Thành Nam - One of the best experts on this subject based on the ideXlab platform.