Condensed Matter Physics最新文献

{"title":"On the existence of a second branch of transverse collective excitations in liquid metals","authors":"J. Wax, N. Jakse","doi":"10.5488/CMP.26.33603","DOIUrl":"https://doi.org/10.5488/CMP.26.33603","url":null,"abstract":"It was found recently that the liquid dynamics of several metals (Li, Zn, Ni, Fe, Tl, Pb) under pressure is characterized by transverse spectral functions containing an additional high-frequency peak. To rationalize the pressure dependence of the contributions from different propagating processes to transverse spectral functions in liquid metals, ab initio molecular dynamics simulations were performed for two typical liquid metals (Na and Al) in a wide range of pressures. The influence of density/pressure is investigated for Na by considering four pressures ranging from 15 to 147 GPa, while the temperature influence is considered for Al between 600 K in the deep supercooled liquid up to 1700 K well above the melting point at ambient pressure. Both temperature and density dependence of the spectra of collective excitations are analyzed with a focus on the appearance of a second high-frequency mode in the transverse spectra. A correspondence between spectra of transverse collective excitations and the peak positions of the Fourier-spectra of velocity autocorrelation functions (vibrational density of states) is found.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"91 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84061274","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}

{"title":"How should a small country respond to climate change?","authors":"A. Haymet","doi":"10.5488/cmp.26.33901","DOIUrl":"https://doi.org/10.5488/cmp.26.33901","url":null,"abstract":"Responses to the global climate crisis often focus on the largest current emitters of greenhouse gases. However, analysis shows that about a third of emissions come from a collection of small emitters, each contributing one- to two-percent of the total additional CO2 injected into the communal atmosphere. Attempts to hold global warming to less than 1.5℃ cannot succeed without also reducing emissions from these small countries.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"777 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78839778","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}

{"title":"An ab initio study of the static, dynamic and electronic properties of some liquid 5d transition metals near melting","authors":"D. González, L. González","doi":"10.5488/CMP.26.33601","DOIUrl":"https://doi.org/10.5488/CMP.26.33601","url":null,"abstract":"We report a study on the static and dynamic properties of several liquid 5d transition metals at thermodynamic conditions near their respective melting points. This is performed by resorting to ab initio molecular dynamics simulations in the framework of the density functional theory. Results are presented for the static structure factors and pair distribution functions; moreover, the local short range order in the liquid metal is also analized. As for the dynamical properties, both single-particle and collective properties are evaluated. The dynamical structure shows the propagating density fluctuations, and the respective dispersion relation is obtained. Results are also obtained for the longitudinal and transverse current spectral functions along with the associated dispersion of collective excitations. For some metals, we found the existence of two branches of transverse collective excitations in the region around the main peak of the structure factor. Finally, several transport coefficients are also calculated.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"163 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89031013","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}

{"title":"Proportional correlation between heat capacity and thermal expansion of atomic, molecular crystals and carbon nanostructures","authors":"M. Barabashko, A. I. Krivchikov, R. Basnukaeva, O. A. Korolyuk, A. Jeżowski","doi":"10.5488/CMP.26.33602","DOIUrl":"https://doi.org/10.5488/CMP.26.33602","url":null,"abstract":"Correlation between thermal expansions β(T) and heat capacity C(T) of atomic and molecular crystals, amorphous materials with a structural disorder, carbon nanomaterials (fullerite C60, bundles SWCNTs of single-walled carbon nanotubes) was analyzed. The influence of the contribution to the coefficient of linear thermal expansion αXe(T) of Xe atoms adsorbed on the SWCNTs bundles is considered. The proportional correlation was found between the contribution to the coefficient of linear thermal expansion αXe(T) and the normalized to the gas constant heat capacity C Xe(T)/R of Xe atoms adsorbed on the SWCNTs bundles. The proportional correlation (β/β*) ∼ (CV/R) with the parameter β* for the bulk thermal expansion coefficient for cryocrystals is proposed. In the case of atomic crystals such as Xe and Ar, the proportional correlation (β/β*) ∼ (CV/R) is observed in the temperature range from the lowest experimental to temperatures where CV/R ≈ 2.3. The correlation is not observed in the temperatures where 2.3 < C V/R < 3 (classical Dulong-Petit law). It was found that the universal proportional correlation is also observed for molecular crystals with linear symmetry, such as CO2, CO, and N2O if the normalized heat capacity below the values CV/R ≈ 3 ÷ 3.5. It indicates that the proportional correlation between thermal expansions (β/β*) and heat capacity (CV/R) is related not only to the translational, but also to the rotational degrees of freedom of the molecule in the crystal. In the case of the C0, molecular crystal with translational and rotational degrees of freedom and intramolecular vibrations, the discussed above correlation occurs below the values of normalized heat capacity CV/R ≈ 7.5. In strongly anisotropic systems, such as systems of compacted bundles of single-walled carbon nanotubes and SWCNTs bundles with adsorbed Xe atoms, this universal dependence appears in a limited temperature range that does not include the lowest temperatures. A qualitative explanation of the observed correlation is proposed.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"74 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85794458","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}

{"title":"Aspects of the microscopic structure of curcumin solutions with water-dimethylsulfoxide solvent. Molecular dynamics computer simulation study","authors":"T. Patsahan, O. Pizio","doi":"10.5488/CMP.26.33605","DOIUrl":"https://doi.org/10.5488/CMP.26.33605","url":null,"abstract":"We explore some aspects of the microscopic structure of curcumin solutions with water-dimethylsulfoxide solvent of variable composition. Molecular dynamics computer simulations at isobaric-isothermal conditions are used for this purpose. The model consists of the OPLS-UA type model for the enol conformer of curcumin (J. Mol. Liq., 223, 707, 2016), the OPLS model for the dimethylsulfoxide (DMSO) and the SPC/E water model. Radial distributions for the centers of mass of curcumin molecules are evaluated and the corresponding running coordination numbers are analyzed. The disaggregation of curcumin clusters upon increasing the DMSO content in water-DMSO solvent is elucidated. Changes of the distribution of water and DMSO species around curcumin molecules are investigated. A qualitative comparison of our findings with the results of other authors is performed. A possibility to relate predictions of the model with the experimental observations in terms of the so-called critical water aggregation percentage is discussed.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"2004 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82963719","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}

{"title":"The fifty-year quest for universality in percolation theory in high dimensions","authors":"Tim Ellis, R. Kenna, B. Berche","doi":"10.5488/CMP.26.33606","DOIUrl":"https://doi.org/10.5488/CMP.26.33606","url":null,"abstract":"Although well described by mean-field theory in the thermodynamic limit, scaling has long been puzzling for finite systems in high dimensions. This raised questions about the efficacy of the renormalization group and foundational concepts such as universality, finite-size scaling and hyperscaling, until recently believed not to be applicable above the upper critical dimension. Significant theoretical progress has been made resolving these issues, and tested in numerous simulational studies of spin models. This progress rests upon superlinearity of correlation length, a notion that for a long time encountered resistance but is now broadly accepted. Percolation theory brings added complications such as proliferation of interpenetrating clusters in apparent conflict with suggestions coming from random-graph asymptotics and a dearth of reliable simulational guidance. Here we report on recent theoretical progress in percolation theory in the renormalization group framework in high dimensions that accommodates superlinear correlation and renders most of the above concepts mutually compatible under different boundary conditions. Results from numerical simulations for free and periodic boundary conditions which differentiate between previously competing theories are also presented. Although still fragmentary, these Monte Carlo results support the new framework which restores the renormalization group and foundational concepts on which it rests.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"18 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78380833","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}

{"title":"Dirac fermion spectrum of the fractional quantum Hall states","authors":"I. N. Karnaukhov","doi":"10.5488/CMP.26.23703","DOIUrl":"https://doi.org/10.5488/CMP.26.23703","url":null,"abstract":"Applying a unified approach, we study the integer quantum Hall effect (IQHE) and fractional quantum Hall effect (FQHE) in the Hofstadter model with short range interactions between fermions. An effective field, that takes into account the interaction between fermions, is determined by both amplitude and phase. Its amplitude is proportional to the interaction strength, the phase corresponds to the minimum energy. In fact, the problem is reduced to the Harper equation with two different scales: the first is a magnetic scale with the cell size corresponding to a unit quantum magnetic flux, the second scale determines the inhomogeneity of the effective field, forms the steady fine structure of the Hofstadter spectrum and leads to the realization of fractional quantum Hall states. In a sample of finite size with open boundary conditions, the fine structure of the Hofstadter spectrum consists of the Dirac branches of the fermion excitations and includes the fine structure of the edge chiral modes. The Chern numbers of the topological Hofstadter bands are conserved during the formation of their fine structure. The edge modes are formed into the Hofstadter bands. They connect the nearest-neighbor subbands and determine the conductance for the fractional filling.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"50 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79941623","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}

{"title":"On the swelling properties of pom-pom polymers: impact of backbone length","authors":"K. Haydukivska, V. Blavatska","doi":"10.5488/CMP.26.23301","DOIUrl":"https://doi.org/10.5488/CMP.26.23301","url":null,"abstract":"The present work continues our previous studies of pom-pom molecule [K. Haydukivska, O. Kalyuzhnyi, V. Blavatska, and J. Ilnytskyi, J. Mol. Liq. 328, 115456 (2021); Condens. Matter Phys. 25, 23302 (2022)]. The molecule consists of a linear backbone with two branching points at both ends, with functionalities f1 and f2. Here, the main attention is concentrated on studying the impact of the central backbone length on the configurational charactersitics of complex molecule, such as size and shape ratios. We apply both a direct polymer renormalization scheme based on continuous chain model and the alternative Wei's method to analyze a set of size and shape properties of pom-pom polymers in dilute solution. The size ratio of a pom-pom and a chain polymer of the same total molecular mass is calculated with an excluded volume interaction taken into account, and estimates for asphericity are found in Gaussian approximation, whereas for the size ratio we found a monotonous dependence of the length of backbone at different functionalities of side arms. Results for asphericity show a non-trivial behaviour.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"22 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82146719","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}

{"title":"Random-anisotropy mixed-spin Ising on a triangular lattice","authors":"E. S. de Santana, A. D. de Arruda, M. Godoy","doi":"10.5488/CMP.26.23601","DOIUrl":"https://doi.org/10.5488/CMP.26.23601","url":null,"abstract":"We have studied the mixed spin-1/2 and 1 Ising ferrimagnetic system with a random anisotropy on a triangular lattice with three interpenetrating sublattices A, B, and C. The spins on the sublattices are represented by σA (states ±1/2), σB (states ±1/2), and SC (states ±1, 0). We have performed Monte Carlo simulations to obtain the phase diagram temperature kBT/|J| versus the strength of the random anisotropy D/|J|. The phase boundary between two ferrimagnetic FR1 and FR2 phases at lower temperatures are always first-order for p < 0.25 and second-order phase transition between the FR1, FR2 and the paramagnetic P phases. On the other hand, for values of p ⪆ 0.5, the phase diagram presents only second-order phase transition lines.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"52 3","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72450829","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}

{"title":"Pressure driven Weyl-topological insulator phase transition in Weyl semimetal SrSi2","authors":"A. Shende, Shiv Kumar Gupta, Ashish Kore, Poorva Singh","doi":"10.5488/CMP.26.23707","DOIUrl":"https://doi.org/10.5488/CMP.26.23707","url":null,"abstract":"Using DFT-based first-principles calculations, we demonstrate the tuning of the electronic structure of Weyl semimetal SrSi2 via external uniaxial strain. The uniaxial strain facilitates the opening of bandgap along Γ-X direction and subsequent band inversion between Si p and Sr d orbitals. Z2 invariants and surface states reveal conclusively that SrSi2 under uniaxial strain is a strong topological insulator. Hence, uniaxial strain drives the semimetallic SrSi2 into fully gapped topological insulating state depicting a semimetal to topological insulator phase transition. Our results highlight the suitability of uniaxial strain to gain control over the topological phase transitions and topological states in SrSi2.","PeriodicalId":10528,"journal":{"name":"Condensed Matter Physics","volume":"28 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84069164","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}