scholarly journals The Jahn–Teller and Pseudo-Jahn–Teller Effects: A Unique and Only Source of Spontaneous Symmetry Breaking in Atomic Matter

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1577
Author(s):  
Isaac B. Bersuker
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
External Perturbation ◽  
Broken Symmetry ◽  
High Symmetry ◽  
Atomic Systems ◽  
Jahn Teller ◽  
Curie Principle ◽  
Adiabatic Potential Energy Surface ◽  
Definition Of

In a mostly review paper, we show that the important problem of symmetry, broken symmetry, and spontaneous broken symmetry of polyatomic systems is directly related to the Jahn–Teller (JT) and pseudo-Jahn–Teller (PJT) effects, including the hidden-JT and hidden-PJT effects, and these JT effects (JTEs) are the only source of spontaneous symmetry breaking in matter. They are directly related to the violation of the adiabatic approximation by the vibronic and other nonadiabatic couplings (jointly termed nonadiabaticity) in the interaction between the electrons and nuclei, which becomes significant in the presence of two or more degenerate or pseudodegenerate electronic states. In a generalization of this understanding of symmetry, we suggest an improved (quantum) definition of stereo-chemical polyatomic space configuration, in which, starting with their high-symmetry configuration, we separate all atomic systems into three distinguishable groups: (1) weak nonadiabaticity, stable high-symmetry configurations; (2) moderate-to-strong nonadiabaticity, unstable high-symmetry configurations, JTEs, spontaneous symmetry breaking (SSB); (3) very strong nonadiabaticity, stable distorted configurations. The JTEs, inherent to the second group of systems, produce a rich variety of novel properties, based on their multiminimum adiabatic potential energy surface (APES), leading to a short lifetime in the distorted configuration. We show the role of the Curie principle in the possibilities to observe the SSB in atomic matter, and mention briefly the revealed recently gamma of novel properties of matter in its interaction with external perturbation that occur due to the SSB, including ferroelectricity and orientational polarization, leading to enhanced permittivity and flexoelectricity.

scholarly journals An introduction to spontaneous symmetry breaking

2019 ◽  
Author(s):  
Aron Beekman ◽  
Louk Rademaker ◽  
Jasper van Wezel
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Condensed Matter ◽  
Topological Defects ◽  
High Energy ◽  
Quantum Corrections ◽  
Gauge Fields ◽  
Singular Limits ◽  
Definition Of ◽  
Goldstone Modes

Perhaps the most important aspect of symmetry in physics is the idea that a state does not need to have the same symmetries as the theory that describes it. This phenomenon is known as spontaneous symmetry breaking. In these lecture notes, starting from a careful definition of symmetry in physics, we introduce symmetry breaking and its consequences. Emphasis is placed on the physics of singular limits, showing the reality of symmetry breaking even in small-sized systems. Topics covered include Nambu-Goldstone modes, quantum corrections, phase transitions, topological defects and gauge fields. We provide many examples from both high energy and condensed matter physics. These notes are suitable for graduate students.

scholarly journals Spontaneous Symmetry-Breaking in the Corrosion Transformation of Ancient Bronzes

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 656
Author(s):  
Yanpeng Yang ◽  
Xiaojuan Cao ◽  
Yang Li ◽  
Zhongchi Wang ◽  
Bingjie Li ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Crystal Lattice ◽  
Spontaneous Symmetry Breaking ◽  
Energy Dispersive Spectrometer ◽  
Optical Microscope ◽  
Corrosion Products ◽  
High Symmetry ◽  
Lattice Type ◽  
General Law ◽  
And Control

In general, during long-term museum conservation, ancient bronzes will generate new corrosion products also called the “secondary corrosion” on the surface of the unearthed “primary corrosion” products due to various environmental conditions. In this paper, the corrosion stages of several ancient Chinese bronzes are characterized by using optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectrometer (Raman). It is found that there exist phase transformation relationships in between the “primary corrosion” and the “secondary corrosion” stages (i.e., (1) the crystal lattice type tends to transform from a high symmetry system to a low symmetry system; (2) in case of the same crystal lattice type, the corrosions exhibit an inter-transformation or symbiosis). It is interesting to note that these transformation rules are very consistent with the well-known physical law of “spontaneous symmetry-breaking”, which won the 2008 Nobel Prize in Physics and also has been considered to be general law of nature, in addition to the principle of Gibbs free energy reduction. The significance of this discovery allows us to achieve the predictability and controllability of the bronze corrosion products (i.e., to predict the corrosive trends in advance and control the “second corrosion” by adjusting the conservation conditions. This research provides a novel conservation concept of ancient bronzes.

scholarly journals Ultrafast imaging of spontaneous symmetry breaking in a photoionized molecular system

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Min Li ◽  
Ming Zhang ◽  
Oriol Vendrell ◽  
Zhenning Guo ◽  
Qianru Zhu ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Molecular System ◽  
Ultrafast Dynamics ◽  
Quantum Molecular Dynamics ◽  
Ultrafast Imaging ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Dynamics Simulations ◽  
Symmetry Space

AbstractThe Jahn-Teller effect is an essential mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to directly image the onset of Jahn-Teller symmetry breaking remains unreached. Here we employ ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution and unambiguously image the ultrafast dynamics of Jahn-Teller deformations of $${{\rm{CH}}}_{4}^{+}$$ CH 4 + cation in symmetry space. It is unraveled that the Jahn-Teller deformation from C3v to C2v geometries takes a characteristic time of 20 ± 7 fs for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C2v structure involving complex revival process of multiple vibrational pathways of the $${{\rm{CH}}}_{4}^{+}$$ CH 4 + cation.

scholarly journals TOPOLOGICAL STABILITY OF BROKEN SYMMETRY ON FUZZY SPHERES

2012 ◽  
Vol 27 (14) ◽  
pp. 1250082 ◽  
Author(s):  
S. DIGAL ◽  
T. R. GOVINDARAJAN
Keyword(s):  
Scalar Field ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Broken Symmetry ◽  
Fuzzy Sphere ◽  
Topological Stability

We study the spontaneous symmetry breaking of O(3) scalar field on a fuzzy sphere [Formula: see text]. We find that the fluctuations in the background of topological configurations are finite. This is in contrast to the fluctuations around a uniform configuration which diverge, due to Mermin–Wagner–Hohenberg–Coleman theorem, leading to the decay of the condensate. Interesting implications of enhanced topological stability of the configurations are pointed out.

scholarly journals Ultrafast imaging of spontaneous symmetry breaking in a photoionized molecular system

2020 ◽  
Author(s):  
Min Li ◽  
Ming Zhang ◽  
Oriol Vendrell ◽  
Zhenning Guo ◽  
Qianru Zhu ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Molecular System ◽  
Real Space ◽  
Ultrafast Dynamics ◽  
Quantum Molecular Dynamics ◽  
Ultrafast Imaging ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Dynamics Simulations

Abstract The Jahn-Teller effect is an essential mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to direct image the onset of Jahn-Teller symmetry breaking remains unreached. Employing ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution, we unambiguously imaged the ultrafast dynamics of Jahn-Teller deformations of CH4+ cation in real space. It is unraveled that the Jahn-Teller deformation from C3v to C2v geometries takes a characteristic time of about 20 femtoseconds for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C2v structure involving complex phasing process of multiple vibrational pathways of the CH4+ cation.

scholarly journals General anomaly matching by Goldstone bosons

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Kazuya Yonekura
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Symmetry Group ◽  
Local Symmetry ◽  
Field Theories ◽  
General Definition ◽  
Four Dimensions ◽  
Goldstone Bosons ◽  
Coset Construction ◽  
Definition Of

Abstract We describe how Goldstone bosons of spontaneous symmetry breaking G → H can reproduce anomalies of UV theories under the symmetry group G at the nonpertur- bative level. This is done by giving a general definition of Wess-Zumino-Witten terms in terms of the invertible field theories in d + 1 dimensions which describe the anomalies of d-dimensional UV theories. The hidden local symmetry $$ \hat{H} $$ H ̂ , which is used to describe Goldstone bosons in coset construction G/H , plays an important role. Our definition also naturally leads to generalized θ-angles of the hidden local gauge group $$ \hat{H} $$ H ̂ . We illustrate this point by SO(Nc) (or Spin(Nc)) QCD-like theories in four dimensions.

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Spontaneous symmetry breaking of dislocation core in SrTiO3

2021 ◽  
pp. 100453
Author(s):  
Hetian Chen ◽  
Di Yi ◽  
Ben Xu ◽  
Jing Ma ◽  
Cewen Nan
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Dislocation Core

scholarly journals Tachyons and Solitons in Spontaneous Symmetry Breaking in the Frame of Field Theory

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1358
Author(s):  
Yiannis Contoyiannis ◽  
Michael P. Hanias ◽  
Pericles Papadopoulos ◽  
Stavros G. Stavrinides ◽  
Myron Kampitakis ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Critical Point ◽  
Universality Class ◽  
Lattice Simulation ◽  
Ginzburg Landau ◽  
Spin Lattice ◽  
Nuclear Collisions ◽  
Ising Spin ◽  
Relativistic Nuclear Collisions

This paper presents our study of the presence of the unstable critical point in spontaneous symmetry breaking (SSB) in the framework of Ginzburg–Landau (G-L) free energy. Through a 3D Ising spin lattice simulation, we found a zone of hysteresis where the unstable critical point continued to exist, despite the system having entered the broken symmetry phase. Within the hysteresis zone, the presence of the kink–antikink SSB solitons expands and, therefore, these can be observed. In scalar field theories, such as Higgs fields, the mass of this soliton inside the hysteresis zone could behave as a tachyon mass, namely as an imaginary quantity. Due to the fact that groups Ζ(2) and SU(2) belong to the same universality class, one expects that, in future experiments of ultra-relativistic nuclear collisions, in addition to the expected bosons condensations, structures of tachyon fields could appear.

scholarly journals Differential Co-Expression Analyses Allow the Identification of Critical Signalling Pathways Altered during Tumour Transformation and Progression

2020 ◽  
Vol 21 (24) ◽  
pp. 9461
Author(s):  
Aurora Savino ◽  
Paolo Provero ◽  
Valeria Poli
Keyword(s):  
Cancer Biology ◽  
Regulatory Networks ◽  
Tumour Progression ◽  
External Perturbation ◽  
Data Types ◽  
Differential Gene ◽  
Gene Regulatory ◽  
Experimental Validations ◽  
Definition Of ◽  
Future Work

Biological systems respond to perturbations through the rewiring of molecular interactions, organised in gene regulatory networks (GRNs). Among these, the increasingly high availability of transcriptomic data makes gene co-expression networks the most exploited ones. Differential co-expression networks are useful tools to identify changes in response to an external perturbation, such as mutations predisposing to cancer development, and leading to changes in the activity of gene expression regulators or signalling. They can help explain the robustness of cancer cells to perturbations and identify promising candidates for targeted therapy, moreover providing higher specificity with respect to standard co-expression methods. Here, we comprehensively review the literature about the methods developed to assess differential co-expression and their applications to cancer biology. Via the comparison of normal and diseased conditions and of different tumour stages, studies based on these methods led to the definition of pathways involved in gene network reorganisation upon oncogenes’ mutations and tumour progression, often converging on immune system signalling. A relevant implementation still lagging behind is the integration of different data types, which would greatly improve network interpretability. Most importantly, performance and predictivity evaluation of the large variety of mathematical models proposed would urgently require experimental validations and systematic comparisons. We believe that future work on differential gene co-expression networks, complemented with additional omics data and experimentally tested, will considerably improve our insights into the biology of tumours.

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