scholarly journals Antisymmetry: Fundamentals and Applications

2020 ◽  
Vol 50 (1) ◽  
pp. 255-281 ◽  
Author(s):  
Hari Padmanabhan ◽  
Jason M. Munro ◽  
Ismaila Dabo ◽  
Venkatraman Gopalan
Keyword(s):  
Time Reversal ◽  
Minimum Energy ◽  
Chemical Species ◽  
Physical World ◽  
State Theory ◽  
Magnetic Structures ◽  
Structures And Properties ◽  
Point Groups ◽  
Arbitrary Dimensions ◽  
Energy Pathways

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, or chemical species. 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 described.

scholarly journals Rock climbing: A local-global algorithm to compute minimum energy and minimum free energy pathways

2017 ◽  
Vol 147 (15) ◽  
pp. 152718 ◽  
Author(s):  
Clark Templeton ◽  
Szu-Hua Chen ◽  
Arman Fathizadeh ◽  
Ron Elber
Keyword(s):  
Free Energy ◽  
Minimum Energy ◽  
Minimum Free Energy ◽  
Rock Climbing ◽  
Global Algorithm ◽  
Energy Pathways

Crystal and Magnetic Structures and Properties of (Lu1–xMnx)MnO3 Solid Solutions

2018 ◽  
Vol 57 (22) ◽  
pp. 14073-14085 ◽  
Author(s):  
Lei Zhang ◽  
Andreas Dönni ◽  
Vladimir Y. Pomjakushin ◽  
Kazunari Yamaura ◽  
Alexei A. Belik
Keyword(s):  
Solid Solutions ◽  
Magnetic Structures ◽  
Structures And Properties ◽  
Crystal And Magnetic Structures

Dual-level direct dynamics study on the hydrogen abstraction reaction of fluorine atom with 1,1-difluoro-1-chloroethane

2011 ◽  
Vol 89 (11) ◽  
pp. 1396-1402 ◽  
Author(s):  
Li Wang ◽  
Song Liu ◽  
Hongqing He ◽  
Jinglai Zhang
Keyword(s):  
Reaction Path ◽  
Hydrogen Abstraction ◽  
Single Point ◽  
Minimum Energy ◽  
State Theory ◽  
Stationary Points ◽  
Kinetic Properties ◽  
Direct Dynamics ◽  
Wide Range ◽  
Major Reaction

The kinetic properties of the reaction of F atoms with CH2H′CF2Cl are investigated by a dual-level direct dynamics method. Optimized geometries and frequencies of all the stationary points and extra points along the minimum-energy path (MEP) are obtained at the MPW1K/6–311+G(d,p) level of theory. Two complexes with energy less than that of the reactants are located in the two reactant paths, respectively. The energy profiles of two reactions are refined with the interpolated single-point energies (ISPE) method at the G3(MP2)/MPW1K level. The rate constants are evaluated using the canonical variational transition state theory (CVT) with a small-curvature tunneling correction (SCT) over a wide range of temperature 200–2000 K. Agreement between the calculated CVT/SCT rate constant and the experimental value is good at 295 K. Our calculations show that the reaction path CH2H′CF2Cl + F → CH2CF2Cl + H′F (Ra) is the major reaction path below 400 K. Moreover, the contribution of CH2H′CF2Cl + F → CHH′CF2Cl + HF (Rb) to the whole reaction increases with the temperature increasing and exceeds path Ra to be the major reaction path.

scholarly journals Discovering minimum energy pathways via distortion symmetry groups

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Jason M. Munro ◽  
Hirofumi Akamatsu ◽  
Haricharan Padmanabhan ◽  
Vincent S. Liu ◽  
Yin Shi ◽  
...  
Keyword(s):  
Minimum Energy ◽  
Symmetry Groups ◽  
Energy Pathways

scholarly journals A historical introduction to the symmetries of magnetic structures. Part 1. Early quantum theory, neutron powder diffraction and the coloured space groups

2017 ◽  
Vol 32 (2) ◽  
pp. 148-155 ◽  
Author(s):  
Andrew S. Wills
Keyword(s):  
Time Reversal ◽  
Magnetic Ordering ◽  
Neutron Powder Diffraction ◽  
Quantum Mechanical ◽  
Langevin Model ◽  
Space Groups ◽  
Magnetic Structures ◽  
Black And White ◽  
Magnetic Symmetry ◽  
Looking Back

This paper introduces the historical development of the symmetries for describing magnetic structures culminating in the derivation of the black and white and coloured space groups. Beginning from the Langevin model of the Curie law, it aims to show the challenges that magnetic ordering presented and how different symmetry frameworks were developed to meet them. As well as explaining core ideas, later papers will show how the different schemes are connected. With these goals in mind, the maths related is kept to the minimum required for clarity. Those wishing to learn more details are invited to engage with the references. As well as looking back and reviewing the development of magnetic symmetry over time, particular attention is spent on explaining where the concept of time-reversal has been applied. That time-reversal has different meaning in classical and quantum mechanical situations, has created confusions which continue to propagate.

scholarly journals Double antisymmetry in magnetic structures

2014 ◽  
Vol 70 (a1) ◽  
pp. C518-C518
Author(s):  
Brian VanLeeuwen ◽  
Mantao Huang ◽  
Daniel Litvin ◽  
Venkatraman Gopalan
Keyword(s):  
Magnetic Structure ◽  
Structure Determination ◽  
Time Reversal ◽  
Time Reversal Symmetry ◽  
Space Group ◽  
Space Groups ◽  
Magnetic Structures ◽  
Recent Introduction ◽  
Symmetry Constraints

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.

ChemInform Abstract: MAGNETIC STRUCTURES AND PROPERTIES OF FEP(1-X)AS(X)

1975 ◽  
Vol 6 (15) ◽  
pp. no-no
Author(s):  
KARI SELTE ◽  
ARNE KJEKSHUS ◽  
TOR A. OFTEDAL ◽  
ARNE F. ANDRESEN
Keyword(s):  
Magnetic Structures ◽  
Structures And Properties
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