The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Eric Collet - One of the best experts on this subject based on the ideXlab platform.
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General Landau theory of non-Symmetry-Breaking and Symmetry-Breaking spin transition materials
Journal of Applied Physics, 2021Co-Authors: Giovanni Azzolina, Roman Bertoni, Eric ColletAbstract:Spin-transition materials, including the families of spin-crossover and charge-transfer systems, and more generally molecular-based materials exhibiting electronic and/or structural bistability, may undergo various types of phase transitions. The change of electronic state is stabilized by molecular reorganizations and both phenomena, which are usually non-Symmetry Breaking, can be described through the evolution of an order parameter q. Due to Symmetry, q linearly couples to volume change. It is known that such elastic interactions are responsible for cooperative phenomena in non-Symmetry-Breaking spin-transitions. However, spin-transition materials may also exhibit Symmetry-Breaking phenomena related to various types of orders such as structural order as well as spin-state concentration waves. The universal framework of the Landau theory of phase transition is relevant for describing such ordering processes through the evolution of a Symmetry-Breaking order parameter h. The simultaneous or sequential occurrence of spin transition and Symmetry Breaking phenomena are reported for numerous spin-transition materials and the coupling between these two types of instabilities is responsible for the emergence of various types of functions. In this work, we use the Landau approach to describe both Symmetry-Breaking phenomena and non-Symmetry-Breaking spin transition. We discuss how their coupling can generate sequences of phase transitions, from simple spin crossover to spin transition, continuous or discontinuous Symmetry Breaking, including ferroelasticity or stepwise spin transitions.
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Landau Theory for Non-Symmetry-Breaking Electronic Instability Coupled to Symmetry-Breaking Applied to Prussian Blue Analogue
Physical Review B, 2020Co-Authors: Giovanni Azzolina, Roman Bertoni, Claude Ecolivet, Hiroko Tokoro, Shin-ichi Ohkoshi, Eric ColletAbstract:Different types of ordering phenomena may occur during phase transitions, described within the universal framework of the Landau theory through the evolution of one, or several, Symmetry-Breaking order parameter . In addition, many systems undergo phase transitions related to an electronic instability, in the absence of a Symmetry-Breaking and eventually described through the evolution of a totally symmetric order parameter q linearly coupled to volume change. Analyzing the coupling of a non-Symmetry-Breaking electronic instability, responsible for volume strain, to Symmetry-Breaking phenomena is of importance for many systems in nature and here we show that the Symmetry-allowed q 2 coupling plays a central role. We use as case study the rubidium manganese hexacyanoferrate Prussian blue analogue, exhibiting phase transitions with hysteresis that may exceed 100 K, and based on intermetallic charge transfer (CT). During the phase transition, the intermetallic CT described through the evolution of q is coupled to cubic-tetragonal ferroelastic Symmetry-Breaking described through the evolution of . In this system, the Symmetry-Breaking and non-Symmetry Breaking deformations have similar amplitudes but the large volume strain is mainly due to CT. We analyze both the ferroelastic and the CT features of the phase transition within the frame of the Landau theory, taking into account the q 2 coupling, stabilizing concomitant CT and Jahn-Teller distortion. The results show that the phase transition and its wide thermal hysteresis originate from the coupling between both processes and that the elastic coupling of each order parameter with the volume strain is responsible for the q 2 coupling. The phase diagrams obtained with this model are in good qualitative agreement with various experimental findings and apply to diverse families of materials undergoing Mott transition, spin-crossover, neutral-ionic transition…, for which isostructural electronic instability driving volume strain can couple to Symmetry-Breaking or not, create phase transition lines and drive cooperative phenomena.
Toby Walsh - One of the best experts on this subject based on the ideXlab platform.
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Symmetry Breaking Constraints: Recent Results
arXiv: Artificial Intelligence, 2012Co-Authors: Toby WalshAbstract:Symmetry is an important problem in many combinatorial problems. One way of dealing with Symmetry is to add constraints that eliminate symmetric solutions. We survey recent results in this area, focusing especially on two common and useful cases: Symmetry Breaking constraints for row and column Symmetry, and Symmetry Breaking constraints for eliminating value Symmetry
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ECAI - Symmetries of Symmetry Breaking Constraints
2010Co-Authors: George Katsirelos, Toby WalshAbstract:Symmetry is an important feature of many constraint programs. We show that any problem Symmetry acting on a set of Symmetry Breaking constraints can be used to break Symmetry. Different symmetries pick out different solutions in each Symmetry class. This simple but powerful idea can be used in a number of different ways. We describe one application within model restarts, a search technique designed to reduce the conflict between Symmetry Breaking and the branching heuristic. In model restarts, we restart search periodically with a random Symmetry of the Symmetry Breaking constraints. Experimental results show that this Symmetry Breaking technique is effective in practice on some standard benchmark problems.
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Symmetries of Symmetry Breaking Constraints
arXiv: Artificial Intelligence, 2009Co-Authors: George Katsirelos, Toby WalshAbstract:Symmetry is an important feature of many constraint programs. We show that any Symmetry acting on a set of Symmetry Breaking constraints can be used to break Symmetry. Different symmetries pick out different solutions in each Symmetry class. We use these observations in two methods for eliminating Symmetry from a problem. These methods are designed to have many of the advantages of Symmetry Breaking methods that post static Symmetry Breaking constraint without some of the disadvantages. In particular, the two methods prune the search space using fast and efficient propagation of posted constraints, whilst reducing the conflict between Symmetry Breaking and branching heuristics. Experimental results show that the two methods perform well on some standard benchmarks.
Giovanni Azzolina - One of the best experts on this subject based on the ideXlab platform.
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General Landau theory of non-Symmetry-Breaking and Symmetry-Breaking spin transition materials
Journal of Applied Physics, 2021Co-Authors: Giovanni Azzolina, Roman Bertoni, Eric ColletAbstract:Spin-transition materials, including the families of spin-crossover and charge-transfer systems, and more generally molecular-based materials exhibiting electronic and/or structural bistability, may undergo various types of phase transitions. The change of electronic state is stabilized by molecular reorganizations and both phenomena, which are usually non-Symmetry Breaking, can be described through the evolution of an order parameter q. Due to Symmetry, q linearly couples to volume change. It is known that such elastic interactions are responsible for cooperative phenomena in non-Symmetry-Breaking spin-transitions. However, spin-transition materials may also exhibit Symmetry-Breaking phenomena related to various types of orders such as structural order as well as spin-state concentration waves. The universal framework of the Landau theory of phase transition is relevant for describing such ordering processes through the evolution of a Symmetry-Breaking order parameter h. The simultaneous or sequential occurrence of spin transition and Symmetry Breaking phenomena are reported for numerous spin-transition materials and the coupling between these two types of instabilities is responsible for the emergence of various types of functions. In this work, we use the Landau approach to describe both Symmetry-Breaking phenomena and non-Symmetry-Breaking spin transition. We discuss how their coupling can generate sequences of phase transitions, from simple spin crossover to spin transition, continuous or discontinuous Symmetry Breaking, including ferroelasticity or stepwise spin transitions.
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Landau Theory for Non-Symmetry-Breaking Electronic Instability Coupled to Symmetry-Breaking Applied to Prussian Blue Analogue
Physical Review B, 2020Co-Authors: Giovanni Azzolina, Roman Bertoni, Claude Ecolivet, Hiroko Tokoro, Shin-ichi Ohkoshi, Eric ColletAbstract:Different types of ordering phenomena may occur during phase transitions, described within the universal framework of the Landau theory through the evolution of one, or several, Symmetry-Breaking order parameter . In addition, many systems undergo phase transitions related to an electronic instability, in the absence of a Symmetry-Breaking and eventually described through the evolution of a totally symmetric order parameter q linearly coupled to volume change. Analyzing the coupling of a non-Symmetry-Breaking electronic instability, responsible for volume strain, to Symmetry-Breaking phenomena is of importance for many systems in nature and here we show that the Symmetry-allowed q 2 coupling plays a central role. We use as case study the rubidium manganese hexacyanoferrate Prussian blue analogue, exhibiting phase transitions with hysteresis that may exceed 100 K, and based on intermetallic charge transfer (CT). During the phase transition, the intermetallic CT described through the evolution of q is coupled to cubic-tetragonal ferroelastic Symmetry-Breaking described through the evolution of . In this system, the Symmetry-Breaking and non-Symmetry Breaking deformations have similar amplitudes but the large volume strain is mainly due to CT. We analyze both the ferroelastic and the CT features of the phase transition within the frame of the Landau theory, taking into account the q 2 coupling, stabilizing concomitant CT and Jahn-Teller distortion. The results show that the phase transition and its wide thermal hysteresis originate from the coupling between both processes and that the elastic coupling of each order parameter with the volume strain is responsible for the q 2 coupling. The phase diagrams obtained with this model are in good qualitative agreement with various experimental findings and apply to diverse families of materials undergoing Mott transition, spin-crossover, neutral-ionic transition…, for which isostructural electronic instability driving volume strain can couple to Symmetry-Breaking or not, create phase transition lines and drive cooperative phenomena.
Liping Zhao - One of the best experts on this subject based on the ideXlab platform.
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GCSE - Symmetry Breaking in Software Patterns
Lecture Notes in Computer Science, 2001Co-Authors: James O. Coplien, Liping ZhaoAbstract:Patterns have a longstanding identity in the scientific community as results of a phenomenon called Symmetry Breaking. This article proposes a formalism for software patterns through connections from software patterns to Symmetry and Symmetry Breaking. Specifically, we show (1) the ties from Alexander's work to Symmetry and Symmetry-Breaking foundations; (2) many programming languages provide constructs that support Symmetry; (3) software patterns are the results of Symmetry Breaking, compensating for design shortfalls in programming languages. The proposed pattern formalism may be useful as a foundation for pattern taxonomies, and to differentiate patterns as a design discipline from heuristics, rules, and arbitrary micro-architectures.
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Symmetry and Symmetry Breaking in Software Patterns
2000Co-Authors: James O. Coplien, Liping ZhaoAbstract:Software patterns draw on the work of the architect Christopher Alexander, which in turn builds on foundations that may be more suitable to software than the architectural metaphors themselves. Patterns have a longstanding identity in the scientific community as results of a phenomenon called Symmetry Breaking. Symmetry Breaking can be defined formally in terms of group theory. We establish formal group-theoretic foundations for several object-oriented programming models and show, by formal constructs and by analogy to other fields, that software patterns reduce to Symmetry Breaking. Such formalisms may be useful as a foundation for pattern taxonomies, and to differentiate patterns as a design discipline from heuristics, rules, and arbitrary microarchitectures.
Roman Bertoni - One of the best experts on this subject based on the ideXlab platform.
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General Landau theory of non-Symmetry-Breaking and Symmetry-Breaking spin transition materials
Journal of Applied Physics, 2021Co-Authors: Giovanni Azzolina, Roman Bertoni, Eric ColletAbstract:Spin-transition materials, including the families of spin-crossover and charge-transfer systems, and more generally molecular-based materials exhibiting electronic and/or structural bistability, may undergo various types of phase transitions. The change of electronic state is stabilized by molecular reorganizations and both phenomena, which are usually non-Symmetry Breaking, can be described through the evolution of an order parameter q. Due to Symmetry, q linearly couples to volume change. It is known that such elastic interactions are responsible for cooperative phenomena in non-Symmetry-Breaking spin-transitions. However, spin-transition materials may also exhibit Symmetry-Breaking phenomena related to various types of orders such as structural order as well as spin-state concentration waves. The universal framework of the Landau theory of phase transition is relevant for describing such ordering processes through the evolution of a Symmetry-Breaking order parameter h. The simultaneous or sequential occurrence of spin transition and Symmetry Breaking phenomena are reported for numerous spin-transition materials and the coupling between these two types of instabilities is responsible for the emergence of various types of functions. In this work, we use the Landau approach to describe both Symmetry-Breaking phenomena and non-Symmetry-Breaking spin transition. We discuss how their coupling can generate sequences of phase transitions, from simple spin crossover to spin transition, continuous or discontinuous Symmetry Breaking, including ferroelasticity or stepwise spin transitions.
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Landau Theory for Non-Symmetry-Breaking Electronic Instability Coupled to Symmetry-Breaking Applied to Prussian Blue Analogue
Physical Review B, 2020Co-Authors: Giovanni Azzolina, Roman Bertoni, Claude Ecolivet, Hiroko Tokoro, Shin-ichi Ohkoshi, Eric ColletAbstract:Different types of ordering phenomena may occur during phase transitions, described within the universal framework of the Landau theory through the evolution of one, or several, Symmetry-Breaking order parameter . In addition, many systems undergo phase transitions related to an electronic instability, in the absence of a Symmetry-Breaking and eventually described through the evolution of a totally symmetric order parameter q linearly coupled to volume change. Analyzing the coupling of a non-Symmetry-Breaking electronic instability, responsible for volume strain, to Symmetry-Breaking phenomena is of importance for many systems in nature and here we show that the Symmetry-allowed q 2 coupling plays a central role. We use as case study the rubidium manganese hexacyanoferrate Prussian blue analogue, exhibiting phase transitions with hysteresis that may exceed 100 K, and based on intermetallic charge transfer (CT). During the phase transition, the intermetallic CT described through the evolution of q is coupled to cubic-tetragonal ferroelastic Symmetry-Breaking described through the evolution of . In this system, the Symmetry-Breaking and non-Symmetry Breaking deformations have similar amplitudes but the large volume strain is mainly due to CT. We analyze both the ferroelastic and the CT features of the phase transition within the frame of the Landau theory, taking into account the q 2 coupling, stabilizing concomitant CT and Jahn-Teller distortion. The results show that the phase transition and its wide thermal hysteresis originate from the coupling between both processes and that the elastic coupling of each order parameter with the volume strain is responsible for the q 2 coupling. The phase diagrams obtained with this model are in good qualitative agreement with various experimental findings and apply to diverse families of materials undergoing Mott transition, spin-crossover, neutral-ionic transition…, for which isostructural electronic instability driving volume strain can couple to Symmetry-Breaking or not, create phase transition lines and drive cooperative phenomena.
