The one-body free volume, which determines the entropy of a hard disk system, has extensive (cavity) and intensive (cell) contributions. So far these contributions have not been unified and considered separately. The presented theory incorporates both contributions, and their sum is shown to determine the free volume and partition function. The approach is based on multiple intersections of the circles concentric with the disks but of twice larger radius. The result is exact formulae for the extensive and intensive entropy contributions in terms of the intersections of just two, three, four, and five circles. The method has an important advantage for applications in numerical simulations: the formulae enable one to convert the disk coordinates into the entropy contribution directly without any additional geometric construction. The theory can be straightforwardly applied to a system of hard spheres.
{"title":"Incorporation of the intensive and extensive entropy contributions in the disk intersection theory of a hard disk system","authors":"V. Pergamenshchik","doi":"10.5488/cmp.26.33501","DOIUrl":"https://doi.org/10.5488/cmp.26.33501","url":null,"abstract":"The one-body free volume, which determines the entropy of a hard disk system, has extensive (cavity) and intensive (cell) contributions. So far these contributions have not been unified and considered separately. The presented theory incorporates both contributions, and their sum is shown to determine the free volume and partition function. The approach is based on multiple intersections of the circles concentric with the disks but of twice larger radius. The result is exact formulae for the extensive and intensive entropy contributions in terms of the intersections of just two, three, four, and five circles. The method has an important advantage for applications in numerical simulations: the formulae enable one to convert the disk coordinates into the entropy contribution directly without any additional geometric construction. The theory can be straightforwardly applied to a system of hard spheres.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88809060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This brief essay commemorates Karl Heinzinger, one of the pioneers in the field of computer modelling of fluid systems, particularly of water and aqueous electrolyte solutions in the bulk phase and near interfaces. Karl Heinzinger died peacefully on January 14, 2023, after a short illness. We express our deepest condolences to his family, colleagues, and friends.
{"title":"Karl Heinzinger and computer modelling of water and aqueous solutions","authors":"A. Trokhymchuk, P. Bopp, E. Spohr, M. Holovko","doi":"10.5488/cmp.26.27001","DOIUrl":"https://doi.org/10.5488/cmp.26.27001","url":null,"abstract":"This brief essay commemorates Karl Heinzinger, one of the pioneers in the field of computer modelling of fluid systems, particularly of water and aqueous electrolyte solutions in the bulk phase and near interfaces. Karl Heinzinger died peacefully on January 14, 2023, after a short illness. We express our deepest condolences to his family, colleagues, and friends.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81802679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In July 2020, our good friend and colleague Taras Bryk turns 60 years old. Today he is one of the leading experts in Ukraine and throughout the world in the field of first-principles and atomistic modeling of liquid metals and alloys, especially their dynamic properties and behavior under extreme conditions, and his scientific works are well cited and known among experts in the field. Since 2021, Taras Bryk is Director of the Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine.
{"title":"First-principles computer modeling and statistical theory in dynamics of liquids. On 60-th anniversary of Taras Bryk","authors":"G. Ruocco, I. Mryglod","doi":"10.5488/cmp.26.30101","DOIUrl":"https://doi.org/10.5488/cmp.26.30101","url":null,"abstract":"In July 2020, our good friend and colleague Taras Bryk turns 60 years old. Today he is one of the leading experts in Ukraine and throughout the world in the field of first-principles and atomistic modeling of liquid metals and alloys, especially their dynamic properties and behavior under extreme conditions, and his scientific works are well cited and known among experts in the field. Since 2021, Taras Bryk is Director of the Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80829990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We relate the the Kubelka-Munk equations for the description of the intensity transfer of light in turbid media to a one-dimensional diffusion equation, which is obtained by averaging the three-dimensional diffusion equation over the lateral directions. This enables us to identify uniquely the Kubelka-Munk parameters and derive expressions for diffuse reflection and transmission coefficients including the effect of internal reflections. Without internal reflections we recover the Kubelka-Munk formulae for these coefficients. We show that the Kubelka-Munk equations are the proper radiative-transfer equations for the one-dimensional diffusion problem.
{"title":"Diffusion of light in turbid media with internal reflections","authors":"W. Schirmacher, G. Ruocco","doi":"10.5488/cmp.26.33604","DOIUrl":"https://doi.org/10.5488/cmp.26.33604","url":null,"abstract":"We relate the the Kubelka-Munk equations for the description of the intensity transfer of light in turbid media to a one-dimensional diffusion equation, which is obtained by averaging the three-dimensional diffusion equation over the lateral directions. This enables us to identify uniquely the Kubelka-Munk parameters and derive expressions for diffuse reflection and transmission coefficients including the effect of internal reflections. Without internal reflections we recover the Kubelka-Munk formulae for these coefficients. We show that the Kubelka-Munk equations are the proper radiative-transfer equations for the one-dimensional diffusion problem.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77510140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The quantitative description of the scientific conference MECO (Middle European Cooperation in Statistical Physics) based on bibliographic records is presented in the paper. Statistics of contributions and participants, co-authorship patterns at the levels of authors and countries, typical proportions of newcomers and permanent participants as well as other characteristics of the scientific event are discussed. The results of this case study contribute to better understanding of the ways of formalization and assessment of conferences and their role in individual academic careers. To highlight the latter, the change of perspective is used: in addition to the general analysis of the conference data, an ego-centric approach is used to emphasize the role of a particular participant for the conference and, vice versa, the role of MECO in the researcher's professional life. This paper is part of the special CMP issue dedicated to the anniversary of Bertrand Berche - a well-known physicist, an active member of the community of authors and editors of the journal, long time collaborator and dear friend of the author.
{"title":"One for all and all for one: on the role of a conference in a scientist's life","authors":"O. Mryglod","doi":"10.5488/CMP.26.13801","DOIUrl":"https://doi.org/10.5488/CMP.26.13801","url":null,"abstract":"The quantitative description of the scientific conference MECO (Middle European Cooperation in Statistical Physics) based on bibliographic records is presented in the paper. Statistics of contributions and participants, co-authorship patterns at the levels of authors and countries, typical proportions of newcomers and permanent participants as well as other characteristics of the scientific event are discussed. The results of this case study contribute to better understanding of the ways of formalization and assessment of conferences and their role in individual academic careers. To highlight the latter, the change of perspective is used: in addition to the general analysis of the conference data, an ego-centric approach is used to emphasize the role of a particular participant for the conference and, vice versa, the role of MECO in the researcher's professional life. This paper is part of the special CMP issue dedicated to the anniversary of Bertrand Berche - a well-known physicist, an active member of the community of authors and editors of the journal, long time collaborator and dear friend of the author.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86104048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Different models are proposed to understand magnetic phase transitions through the prism of competition between the energy and the entropy. One of such models is a q-state Potts model with invisible states. This model introduces r invisible states such that if a spin lies in one of them, it does not interact with the rest states. We consider such a model using the mean field approximation on an annealed scale-free network where the probability of a randomly chosen vertex having a degree k is governed by the power-law P(k) ∝ k λ. Our results confirm that q, r and λ play a role of global parameters that influence the critical behaviour of the system. Depending on their values, the phase diagram is divided into three regions with different critical behaviours. However, the topological influence, presented by the marginal value of λc(q), has proven to be dominant over the entropic influence, governed by the number of invisible states r.
{"title":"Potts model with invisible states on a scale-free network","authors":"P. Sarkanych, M. Krasnytska","doi":"10.5488/CMP.26.13507","DOIUrl":"https://doi.org/10.5488/CMP.26.13507","url":null,"abstract":"Different models are proposed to understand magnetic phase transitions through the prism of competition between the energy and the entropy. One of such models is a q-state Potts model with invisible states. This model introduces r invisible states such that if a spin lies in one of them, it does not interact with the rest states. We consider such a model using the mean field approximation on an annealed scale-free network where the probability of a randomly chosen vertex having a degree k is governed by the power-law P(k) ∝ k λ. Our results confirm that q, r and λ play a role of global parameters that influence the critical behaviour of the system. Depending on their values, the phase diagram is divided into three regions with different critical behaviours. However, the topological influence, presented by the marginal value of λc(q), has proven to be dominant over the entropic influence, governed by the number of invisible states r.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89418900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The long-time behaviour of spin-spin correlators in the slow relaxation of systems undergoing phase-ordering kinetics is studied in geometries of finite size. A phenomenological finite-size scaling ansatz is formulated and tested through the exact solution of the kinetic spherical model, quenched to below the critical temperature, in 2< d < 4 dimensions.
在有限尺寸的几何结构中，研究了自旋-自旋相关器在经历相序动力学的慢弛豫系统中的长时间行为。通过动力学球面模型的精确解，在2< d < 4维中淬火至临界温度以下，建立了一个有限尺寸的现象学尺度分析模型并对其进行了测试。
{"title":"Non-equilibrium relaxations: ageing and finite-size effects","authors":"M. Henkel","doi":"10.5488/CMP.26.13501","DOIUrl":"https://doi.org/10.5488/CMP.26.13501","url":null,"abstract":"The long-time behaviour of spin-spin correlators in the slow relaxation of systems undergoing phase-ordering kinetics is studied in geometries of finite size. A phenomenological finite-size scaling ansatz is formulated and tested through the exact solution of the kinetic spherical model, quenched to below the critical temperature, in 2< d < 4 dimensions.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75221173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The majority-voter model is studied by Monte Carlo simulations on hypercubic lattices of dimension d = 2 to 7 with periodic boundary conditions. The critical exponents associated to the finite-size scaling of the magnetic susceptibility are shown to be compatible with those of the Ising model. At dimension d = 4, the numerical data are compatible with the presence of multiplicative logarithmic corrections. For d ≥ 5, the estimates of the exponents are close to the prediction d/2 when taking into account the dangerous irrelevant variable at the Gaussian fixed point. Moreover, the universal values of the Binder cumulant are also compatible with those of the Ising model. This indicates that the upper critical dimension of the majority-voter model is not dc = 6 as claimed in the literature, but dc = 4 like the equilibrium Ising model.
{"title":"Finite-size scaling of the majority-voter model above the upper critical dimension","authors":"Christophe Chatelain","doi":"10.5488/CMP.26.13202","DOIUrl":"https://doi.org/10.5488/CMP.26.13202","url":null,"abstract":"The majority-voter model is studied by Monte Carlo simulations on hypercubic lattices of dimension d = 2 to 7 with periodic boundary conditions. The critical exponents associated to the finite-size scaling of the magnetic susceptibility are shown to be compatible with those of the Ising model. At dimension d = 4, the numerical data are compatible with the presence of multiplicative logarithmic corrections. For d ≥ 5, the estimates of the exponents are close to the prediction d/2 when taking into account the dangerous irrelevant variable at the Gaussian fixed point. Moreover, the universal values of the Binder cumulant are also compatible with those of the Ising model. This indicates that the upper critical dimension of the majority-voter model is not dc = 6 as claimed in the literature, but dc = 4 like the equilibrium Ising model.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84627694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Motivated by the compound LiHoxY1-xF4, we consider the Ising chain with random couplings and in the presence of simultaneous random transverse and longitudinal fields, and study its low-energy properties at zero temperature by the strong disorder renormalization group approach. In the absence of longitudinal fields, the system exhibits a quantum-ordered and a quantum-disordered phase separated by a critical point of infinite disorder. When the longitudinal random field is switched on, the ordered phase vanishes and the trajectories of the renormalization group are attracted to two disordered fixed points: one is characteristic of the classical random field Ising chain, the other describes the quantum disordered phase. The two disordered phases are separated by a separatrix that starts at the infinite disorder fixed point and near which there are strong quantum fluctuations.
{"title":"Random Ising chain in transverse and longitudinal fields: Strong disorder RG study","authors":"Tam'as PetHo, Ferenc Igl'oi, Istv'an A. Kov'acs","doi":"10.5488/CMP.26.13102","DOIUrl":"https://doi.org/10.5488/CMP.26.13102","url":null,"abstract":"Motivated by the compound LiHoxY1-xF4, we consider the Ising chain with random couplings and in the presence of simultaneous random transverse and longitudinal fields, and study its low-energy properties at zero temperature by the strong disorder renormalization group approach. In the absence of longitudinal fields, the system exhibits a quantum-ordered and a quantum-disordered phase separated by a critical point of infinite disorder. When the longitudinal random field is switched on, the ordered phase vanishes and the trajectories of the renormalization group are attracted to two disordered fixed points: one is characteristic of the classical random field Ising chain, the other describes the quantum disordered phase. The two disordered phases are separated by a separatrix that starts at the infinite disorder fixed point and near which there are strong quantum fluctuations.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85970052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We use a density functional approach to calculate the contact angle of the water model on a heterogeneous, graphite-like surface. The surface heterogeneity results from the pre-adsorption of a layer of spherical species. The pre-adsorbed molecules can also be a mixture of molecules of different sizes. The presence of pre-adsorbed layer causes geometrical and energetical heterogeneity of the surfaces. Two cases are considered. The pre-adsorbed molecules can either behave like hard-sphere obstacles, or they can also attract the molecules of water. In the first case, an increase of the amount of pre-adsorbed species leads to an increase of the wetting temperature, but this increase does not depend linearly on the amount of obstacles. In the case of obstacles exerting attractive forces on water molecules, the curves describing the dependence between the amount of pre-adsorbed species and the contact angle can exhibit a maximum. In addition, we have also studied how the pre-adsorbed species influence the local densities of gaseous and liquid phases in contact with a modified solid surface.
{"title":"Contact angle of water on a model heterogeneous surface. A density functional approach","authors":"K. Dąbrowska, O. Pizio, S. Sokołowski","doi":"10.5488/CMP.25.33603","DOIUrl":"https://doi.org/10.5488/CMP.25.33603","url":null,"abstract":"We use a density functional approach to calculate the contact angle of the water model on a heterogeneous, graphite-like surface. The surface heterogeneity results from the pre-adsorption of a layer of spherical species. The pre-adsorbed molecules can also be a mixture of molecules of different sizes. The presence of pre-adsorbed layer causes geometrical and energetical heterogeneity of the surfaces. Two cases are considered. The pre-adsorbed molecules can either behave like hard-sphere obstacles, or they can also attract the molecules of water. In the first case, an increase of the amount of pre-adsorbed species leads to an increase of the wetting temperature, but this increase does not depend linearly on the amount of obstacles. In the case of obstacles exerting attractive forces on water molecules, the curves describing the dependence between the amount of pre-adsorbed species and the contact angle can exhibit a maximum. In addition, we have also studied how the pre-adsorbed species influence the local densities of gaseous and liquid phases in contact with a modified solid surface.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81399572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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