scholarly journals Band Representations and Topological Quantum Chemistry

Author(s):  
Jennifer Cano ◽  
Barry Bradlyn

In this article, we provide a pedagogical review of the theory of topological quantum chemistry and topological crystalline insulators. We begin with an overview of the properties of crystal symmetry groups in position and momentum space. Next, we introduce the concept of a band representation, which quantifies the symmetry of topologically trivial band structures. By combining band representations with symmetry constraints on the connectivity of bands in momentum space, we show how topologically nontrivial bands can be cataloged and classified. We present several examples of new topological phases discovered using this paradigm and conclude with an outlook toward future developments. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Author(s):  
Philippe Ghosez ◽  
Javier Junquera

Taking a historical perspective, we provide a brief overview of the first-principles modeling of ferroelectric perovskite oxides over the past 30 years. We emphasize how the work done by a relatively small community on the fundamental understanding of ferroelectricity and related phenomena has been at the origin of consecutive theoretical breakthroughs, with an impact going often well beyond the limit of the ferroelectric community. In this context, we first review key theoretical advances such as the modern theory of polarization, the computation of functional properties as energy derivatives, the explicit treatment of finite fields, or the advent of second-principles methods to extend the length and timescale of the simulations. We then discuss how these have revolutionized our understanding of ferroelectricity and related phenomena in this technologically important class of compounds. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Ryan J. Emenecker ◽  
Alex S. Holehouse ◽  
Lucia C. Strader

A surge in research focused on understanding the physical principles governing the formation, properties, and function of membraneless compartments has occurred over the past decade. Compartments such as the nucleolus, stress granules, and nuclear speckles have been designated as biomolecular condensates to describe their shared property of spatially concentrating biomolecules. Although this research has historically been carried out in animal and fungal systems, recent work has begun to explore whether these same principles are relevant in plants. Effectively understanding and studying biomolecular condensates require interdisciplinary expertise that spans cell biology, biochemistry, and condensed matter physics and biophysics. As such, some involved concepts may be unfamiliar to any given individual. This review focuses on introducing concepts essential to the study of biomolecular condensates and phase separation for biologists seeking to carry out research in this area and further examines aspects of biomolecular condensates that are relevant to plant systems. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Paul A. McClarty

At sufficiently low temperatures, magnetic materials often enter correlated phases hosting collective, coherent magnetic excitations such as magnons or triplons. Drawing on the enormous progress on topological materials of the past few years, recent research has led to new insights into the geometry and topology of these magnetic excitations. Berry phases associated with magnetic dynamics can lead to observable consequences in heat and spin transport, whereas analogs of topological insulators and semimetals can arise within magnon band structures from natural magnetic couplings. Magnetic excitations offer a platform to explore the interplay of magnetic symmetries and topology, to drive topological transitions using magnetic fields; examine the effects of interactions on topological bands; and generate topologically protected spin currents at interfaces. In this review, we survey progress on all these topics, highlighting aspects of topological matter that are unique to magnon systems and the avenues yet to be fully investigated. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Takaaki Dohi ◽  
Robert. M. Reeve ◽  
Mathias Kläui

In condensed matter physics, magnetic skyrmions, topologically stabilized magnetic solitons, have been discovered in various materials systems, which has intrigued the community in terms of not only fundamental physics but also with respect to engineering applications. In particular, skyrmions in thin films are easily manipulable by electrical means even at room temperature. Concomitantly, a variety of possible applications have been proposed and proof-of-concept devices have been demonstrated. Recently, the field of skyrmion-based electronics has been referred to as skyrmionics and this field has been rapidly growing and extended in multiple directions. This review provides recent progress for skyrmion research in thin film systems and we discuss promising new directions, which will further invigorate the field. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
José Ruiz-Franco ◽  
Emanuela Zaccarelli

In this review, we discuss recent advances in the investigation of colloidal systems interacting via a combination of short-range attraction and long-range repulsion. The prototypical examples of this phenomenology are charged colloids with depletion interactions, but the results apply, to a large extent, also to suspensions of globular proteins, clays, and, in general, to systems with competing attractive (hydrophobic) and repulsive (polar) contributions. After a brief introduction to the problem, we focus on the three disordered states that characterize these systems: equilibrium cluster phase, equilibrium gel, and Wigner glass of clusters. We provide a comparison of their static and dynamic observables, mainly by means of numerical simulations. Next, we discuss the few available studies on their viscoelastic properties and on their response to an external shear. Finally, we provide a summary of the current findings and also raise the main open questions and challenges for the future in this topic. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Subhadip Ghosh ◽  
Ambika Somasundar ◽  
Ayusman Sen

Nature has designed multifaceted cellular structures to support life. Cells contain a vast array of enzymes that collectively perform essential tasks by harnessing energy from chemical reactions. Despite the complexity, intra- and intercellular motility at low Reynolds numbers remain the epicenter of life. In the past decade, detailed investigations on enzymes that are freely dispersed in solution have revealed concentration-dependent enhanced diffusion and chemotactic behavior during catalysis. Theoretical calculations and simulations have determined the magnitude of the impulsive force per turnover; however, an unequivocal consensus regarding the mechanism of enhanced diffusion has not been reached. Furthermore, this mechanical force can be transferred from the active enzymes to inert particles or surrounding fluid, thereby providing a platform for the design of biomimetic systems. Understanding the factors governing enzyme motion would help us to understand organization principles for dissipative self-assembly and the fabrication of molecular machines. The purpose of this article is to review the different classes of enzyme motility and discuss the possible mechanisms as gleaned from experimental observations and theoretical modeling. Finally, we focus on the relevance of enzyme motion in biology and its role in future applications. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Edouard Brézin

My life as a physicist has been a blend of field theory, statistical physics, and condensed matter physics over half a century. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Michael J. Lynch ◽  
Michael A. Long

Green criminology has developed into a criminological subfield with a substantial literature. That literature is so vast that a single review cannot do it justice. This article examines the definition of green crime, the historical development of green criminology, some major areas of green criminological research, and potential future developments. Unlike traditional criminology with its focus on human victims, green criminology recognizes that various living entities can be victims of the ways in which humans harm ecosystems. Green research thus explores crime, victimization, and justice from several theoretical positions that acknowledge these unique victims. Although green criminology contains several approaches, this review primarily focuses on political economic green criminology. The section titled The Definition, Overview, and Historical Development of Green Criminology identifies, but does not review in depth, other forms of green criminology. Expected final online publication date for the Annual Review of Criminology, Volume 5 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Bertrand I. Halperin

Over the course of my career, I have had the opportunity to work on a wide variety of problems in condensed matter physics, benefiting from superb collaborators and environments full of inspiring colleagues. I review here some highlights of my journey so far. Subjects include theories of dynamic critical phenomena, phase transitions in two-dimensional systems, systems with strong disorder, quantum physics of mesoscopic systems, one-dimensional quantum systems, and the quantum Hall effects. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 12 is March 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


Author(s):  
Elliott S. Chiu ◽  
Sue VandeWoude

Endogenous retroviruses (ERVs) serve as markers of ancient viral infections and provide invaluable insight into host and viral evolution. ERVs have been exapted to assist in performing basic biological functions, including placentation, immune modulation, and oncogenesis. A subset of ERVs share high nucleotide similarity to circulating horizontally transmitted exogenous retrovirus (XRV) progenitors. In these cases, ERV–XRV interactions have been documented and include ( a) recombination to result in ERV–XRV chimeras, ( b) ERV induction of immune self-tolerance to XRV antigens, ( c) ERV antigen interference with XRV receptor binding, and ( d) interactions resulting in both enhancement and restriction of XRV infections. Whereas the mechanisms governing recombination and immune self-tolerance have been partially determined, enhancement and restriction of XRV infection are virus specific and only partially understood. This review summarizes interactions between six unique ERV–XRV pairs, highlighting important ERV biological functions and potential evolutionary histories in vertebrate hosts. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 9 is February 16, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


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