1,588 research outputs found
Algebraic conformal quantum field theory in perspective
Conformal quantum field theory is reviewed in the perspective of Axiomatic,
notably Algebraic QFT. This theory is particularly developped in two spacetime
dimensions, where many rigorous constructions are possible, as well as some
complete classifications. The structural insights, analytical methods and
constructive tools are expected to be useful also for four-dimensional QFT.Comment: Review paper, 40 pages. v2: minor changes and references added, so as
to match published versio
Recommended from our members
Visualization of Tensor Fields in Mechanics
Tensors are used to describe complex physical processes in many applications. Examples include the distribution of stresses in technical materials, acting forces during seismic events, or remodeling of biological tissues. While tensors encode such complex information mathematically precisely, the semantic interpretation of a tensor is challenging. Visualization can be beneficial here and is frequently used by domain experts. Typical strategies include the use of glyphs, color plots, lines, and isosurfaces. However, data complexity is nowadays accompanied by the sheer amount of data produced by large-scale simulations and adds another level of obstruction between user and data. Given the limitations of traditional methods, and the extra cognitive effort of simple methods, more advanced tensor field visualization approaches have been the focus of this work. This survey aims to provide an overview of recent research results with a strong application-oriented focus, targeting applications based on continuum mechanics, namely the fields of structural, bio-, and geomechanics. As such, the survey is complementing and extending previously published surveys. Its utility is twofold: (i) It serves as basis for the visualization community to get an overview of recent visualization techniques. (ii) It emphasizes and explains the necessity for further research for visualizations in this context
Computational characterization and prediction of metal-organic framework properties
In this introductory review, we give an overview of the computational
chemistry methods commonly used in the field of metal-organic frameworks
(MOFs), to describe or predict the structures themselves and characterize their
various properties, either at the quantum chemical level or through classical
molecular simulation. We discuss the methods for the prediction of crystal
structures, geometrical properties and large-scale screening of hypothetical
MOFs, as well as their thermal and mechanical properties. A separate section
deals with the simulation of adsorption of fluids and fluid mixtures in MOFs
A Planning-and-Exploring Approach to Extreme-Mechanics Force Fields
Extreme mechanical processes such as strong lattice distortion and bond
breakage during fracture are ubiquitous in nature and engineering, which often
lead to catastrophic failure of structures. However, understanding the
nucleation and growth of cracks is challenged by their multiscale
characteristics spanning from atomic-level structures at the crack tip to the
structural features where the load is applied. Molecular simulations offer an
important tool to resolve the progressive microstructural changes at crack
fronts and are widely used to explore processes therein, such as mechanical
energy dissipation, crack path selection, and dynamic instabilities (e.g.,
kinking, branching). Empirical force fields developed based on local
descriptors based on atomic positions and the bond orders do not yield
satisfying predictions of fracture, even for the nonlinear, anisotropic
stress-strain relations and the energy densities of edges. High-fidelity force
fields thus should include the tensorial nature of strain and the energetics of
rare events during fracture, which, unfortunately, have not been taken into
account in both the state-of-the-art empirical and machine-learning force
fields. Based on data generated by first-principles calculations, we develop a
neural network-based force field for fracture, NN-F, by combining
pre-sampling of the space of strain states and active-learning techniques to
explore the transition states at critical bonding distances. The capability of
NN-F is demonstrated by studying the rupture of h-BN and twisted bilayer
graphene as model problems. The simulation results confirm recent experimental
findings and highlight the necessity to include the knowledge of electronic
structures from first-principles calculations in predicting extreme mechanical
processes
Recommended from our members
Recent Mathematical Developments in Quantum Field Theory
This workshop has focused on three areas in mathematical quantum field theory and their interrelations: 1) conformal field theory, 2) constructions of interacting models of quantum field theory by various methods, and 3) several approaches studying the interplay of quantum field theory and gravity
Generalized liquid crystals: giant fluctuations and the vestigial chiral order of , and matter
The physics of nematic liquid crystals has been subject of intensive research
since the late 19th century. However, because of the limitations of chemistry
the focus has been centered around uni- and biaxial nematics associated with
constituents bearing a or symmetry respectively. In
view of general symmetries, however, these are singularly special since nematic
order can in principle involve any point group symmetry. Given the progress in
tailoring nano particles with particular shapes and interactions, this vast
family of "generalized nematics" might become accessible in the laboratory.
Little is known since the order parameter theories associated with the highly
symmetric point groups are remarkably complicated, involving tensor order
parameters of high rank. Here we show that the generic features of the
statistical physics of such systems can be studied in a highly flexible and
efficient fashion using a mathematical tool borrowed from high energy physics:
discrete non-Abelian gauge theory. Explicitly, we construct a family of lattice
gauge models encapsulating nematic ordering of general three dimensional point
group symmetries. We find that the most symmetrical "generalized nematics" are
subjected to thermal fluctuations of unprecedented severity. As a result, novel
forms of fluctuation phenomena become possible. In particular, we demonstrate
that a vestigial phase carrying no more than chiral order becomes ubiquitous
departing from high point group symmetry chiral building blocks, such as ,
and symmetric matter.Comment: 14 pages, 5 figures; published versio
Recent mathematical developments in quantum field theory
This workshop has focused on three areas in mathematical quantum field theory and their interrelations: 1) conformal field theory, 2) constructions of interacting models of quantum field theory by various methods, and 3) several approaches studying the interplay of quantum field theory and gravit
- …