Thermodynamic Phase Transition Research Articles

Effect of dark energy on photon orbits and thermodynamic phase transition for Hayward anti-de Sitter black holes

We investigate a black hole solution analogous to Hayward regular black holes with a negative cosmological constant surrounded by quintessence — the Hayward–Kiselev anti-de Sitter (AdS) black hole, derived from Einstein equations coupled with nonlinear electrodynamics. The solution reveals a singularity due to the quintessential dark energy, and we have outlined the conditions necessary for regularity. When pressure, e.g., P=0.016, the effect of quintessential dark energy results in an otherwise absent van der Waal phase transition and second-order phase transition. Interestingly, the impact of dark energy decreases critical temperature (Tc), whereas critical pressure (Pc) increases. Investigating the correlation between photon sphere radius and the first-order phase transition exhibited non-monotonic behaviour among the photon sphere radius, nonlinear charge parameter, temperature, and pressure under certain conditions. Variations in the photon sphere radius and impact parameter before and after the phase transition serve as order parameters. The critical exponents Δrps and Δups near the critical point consistently approach 1/2, suggesting that rps and ups can be order parameters for black hole phase transitions and indicating a potential universal gravitational relationship near the critical point within a black hole thermodynamic system. We also analyzed the previously unexplored Kiselev-AdS black hole, which emerges as a particular case in the limit g→0.

Two liquid states of distinguishable helium-4: The existence of another non-superfluid frozen by heating.

We show that two liquid states can exist in distinguishable helium-4 (4He) obeying Boltzmann statistics by path integral centroid molecular dynamics (CMD) simulations. This is an indication of quantum liquid polyamorphism induced by the nuclear quantum effect. For 0.08-3.3K and 1-500bar, we extensively conducted the isothermal-isobaric CMD simulations to explore not only possible states and state diagram but also the state characteristics. The distinguishable 4He below 25bar does not freeze down to 0.1K even though it includes no Bosonic exchange effect and, therefore, no Bose condensation. One liquid state, low quantum-dispersion liquid (LQDL), is nearly identical to normal liquid He-I of real 4He. The other is high quantum-dispersion liquid (HQDL) consisting of atoms with longer quantum wavelength. This is another non-superfluid existing below 0.5K or the temperatures of LQDL. The HQDL is also a low-entropy and fragile liquid to exhibit, unlike conventional liquids, rather gas-like relaxation of velocity autocorrelation function, while there the atoms diffuse without noticeable contribution from quantum tunneling. The LQDL-HQDL transition is not a thermodynamic phase transition but a continuous crossover accompanied by the change in the expansion factor of quantum wavelength. Freezing of HQDL into the low quantum-dispersion amorphous solid occurs by heating from 0.2 to 0.3K at 40-50bar, while this P-T condition coincides with the Kim-Chan normal-supersolid phase boundary of real 4He. The obtained state diagram was compared to that of the confined subnano-scale 4He systems, where Bosonic correlation is considerably suppressed.

Thermodynamic Phase Transition of AdS Black Holes in Massive Gravity on Free Energy Landscape

Thermodynamic Phase Transition of AdS Black Holes in Massive Gravity on Free Energy Landscape

Holographic thermodynamics of a charged AdS black holes with global monopole

Abstract By regarding the Newton constant GN and cosmological constant Λ as variables, we in this paper study the thermodynamics and phase transition of Reissner-Nordström anti-de Sitter (RN-AdS) black hole with global monopole in the framework of AdS/CFT correspondence. It is found that there are interesting critical phenomena and phase behaviors in the (grand) canonical ensembles of fixed (Q, V, C), (Φ, V, C) and (Q, V, μ). When the other parameters are fixed, the free energy increases with the global monopole increases. In (Q, V, C) ensemble, the range of unstable region increases with the increase of global monopole. In (Φ, V, C) ensemble, when Φ<Φc, the free energy appears two branches, the upper and lower branches correspond to low entropy and high entropy respectively. When (Q, V, μ) is fixed, a new zero-order phase transition occurs in the high-entropy phase and the low-entropy phase at certain μ-dependent temperatures. When μ increases to a certain value, this zero-order phase transition disappears. This certain value is positively related to the magnitude of the global monopole. Finally, we find that p-V criticality does not appear with the change of global monopole. Therefore, it is important to note that the CFT states of charged black holes with global monopole do not correspond to Van der Waals fluids. Finally, we find that charged black holes with global monopoles can better reflect thermodynamic phase transitions and critical phenomena under the AdS/CFT correspondence. By adjusting the change of the global monopole, the thermodynamic phase transition will also change.

Topological classes of thermodynamics of the static multi-charge AdS black holes in gauged supergravities: novel temperature-dependent thermodynamic topological phase transition

In this paper, we investigate, in the framework of the topological approach to black hole thermodynamics, using the generalized off-shell Helmholtz free energy, the topological numbers of the static multi-charge AdS black holes in four- and five-dimensional gauged supergravities. We find that the topological number of the static-charged AdS black holes in four-dimensional Kaluza-Klein (K-K) gauged supergravity theory is W = 0, while that of the static-charged AdS black holes in four-dimensional gauged –iX0X1-supergravity and STU gauged supergravity theories, and five-dimensional Einstein-Maxwell-dilaton-axion (EMDA) gauged supergravity and STU gauged supergravity, and five-dimensional static-charged AdS Horowitz-Sen black hole are both W = 1. Furthermore, we observe a novel temperature-dependent thermodynamic topological phase transition that can happen in the four-dimensional static-charged AdS black hole in EMDA gauged supergravity theory, the four-dimensional static-charged AdS Horowitz-Sen black hole, and the five-dimensional static-charged AdS black hole in K-K gauged supergravity theory. We believe that the novel temperature-dependent thermodynamic topological phase transition could help us better understand black hole thermodynamics and, further, shed new light on the fundamental nature of gauged supergravity theories.

Change point detection of events in molecular simulations using dupin

Particle tracking is commonly used to study time-dependent behavior in many different types of physical and chemical systems involving constituents that span many length scales, including atoms, molecules, nanoparticles, granular particles, and even larger objects. Behaviors of interest studied using particle tracking information include disorder-order transitions, thermodynamic phase transitions, structural transitions, protein folding, crystallization, gelation, swarming, avalanches and fracture. A common challenge in studies of these systems involves change detection. Change point detection discerns when a temporal signal undergoes a change in distribution. These changes can be local or global, instantaneous or prolonged, obvious or subtle. Moreover, system-wide changes marking an interesting physical or chemical phenomenon (e.g. crystallization of a liquid) are often preceded by events (e.g. pre-nucleation clusters) that are localized and can occur anywhere at anytime in the system. For these reasons, detecting events in particle trajectories generated by molecular simulation is challenging and typically accomplished via ad hoc solutions unique to the behavior and system under study. Consequently, methods for event detection lack generality, and those used in one field are not easily used by scientists in other fields. Here we present a new Python-based tool, dupin, that allows for universal event detection from particle trajectory data irrespective of the system details. dupin works by creating a signal representing the simulation and partitioning the signal based on events (changes within the trajectory). This approach allows for studies where manual annotating of event boundaries would require a prohibitive amount of time. Furthermore, dupin can serve as a tool in automated and reproducible workflows. We demonstrate the application of dupin using three examples and discuss its applicability to a wider class of problems. Program summaryProgram Title:dupinCPC Library link to program files:https://doi.org/10.17632/kjcn97zc46.1%Developer's repository link::https://github.com/glotzerlab/dupinLicensing provisions: BSD 3-clauseProgramming language: PythonNature of problem: In the field of molecular simulations, detecting structural transitions or events within trajectories can be both challenging and time-consuming for larger studies due to the requirement of a manual approach. This issue is particularly pronounced in studies involving hundreds or thousands of simulations, where manual detection and analysis of transitions become infeasible. Our goal is to develop an automated, accurate and efficient method for detecting transition points in simulation trajectories, which both saves time and aids researchers in uncovering important events and their underlying causes in various systems. Additionally, we aim to facilitate new machine learning applications to important materials problems such as predicting and designing crystallization pathways, predicting defect formation, and describing the behavior of active matter, all of which involve structural transitions occurring over time. The developed method should be applicable to offline and online detection, enabling event-dependent triggers for advanced simulation/experimental protocols and efficient processing and storing of data.Solution method: We develop a versatile python package called dupin for detecting molecular events and structural transitions in simulation trajectories. dupin's workflow pipeline includes three major stages: data preprocessing, data augmentation, and detection. The components of this pipeline collectively improve the accuracy and efficiency of identifying structural changes in particle trajectory data. In data preprocessing, we generate and aggregate data into a comprehensive representation of the system. Data augmentation techniques such as feature selection and dimensionality reduction counteract the noise arising from high-dimensional data and enhance computational performance. We detect change points within the trajectory indicating transition events using a cost-based event detection method. In dupin, we implement two cost functions based on piecewise linear fits, which offer different levels of sensitivity to sudden shifts and changes in the signal. The package can use any cost-based detection algorithm but has a special interface for the Python package ruptures. Regardless of detection algorithm, we use the cost function and “elbow” detection to determine the correct number of change points. The detection scheme can be applied both offline and online, enabling real-time analysis of molecular events as simulations progress. As an example, dupin may be used to trigger a high frequency storage of frames within a simulation upon nucleation and subsequent solidification of a liquid into a crystal. Our method demonstrates a high degree of accuracy in detecting transition points within simulation trajectories when provided with informative descriptors. By automating the detection process, our solution enables efficient change point detection for studies with large-scale simulations.Additional comments including restrictions and unusual features: Our package, dupin, has great promise in detecting transition points within simulation trajectories with a high degree of accuracy; nonetheless, it is essential to note that it relies heavily on the selection of informative descriptors. The accuracy of the detection may be compromised if the chosen descriptors do not effectively capture the changes in a system's properties. However, this restriction can be mitigated by selecting a diverse range of descriptors and applying a feature selection tool to refine the signal.

Heat capacity study of fatty acids as phase change materials for thermal energy storage

Fatty acids are commonly used as phase change materials (PCMs) for thermal energy storage due to their high latent heat, non-toxicity, and biocompatibility. However, the thermodynamic properties of fatty acids have not been systematically studied, especially for their heat capacity data over a wide temperature range. This limitation greatly restricts their practical applications in designing and constructing fatty acids based PCMs and corresponding thermal management techniques. Herein, the heat capacities of a series of fatty acids (octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid) have been measured using a combined relaxation, adiabatic, and differential scanning calorimetry techniques over a temperature range from 1.9 K to 380 K. The corresponding thermodynamic functions and phase transition thermodynamic parameters have been calculated based on heat capacity data fitting. Additionally, the thermal stability and thermal conductivity of these fatty acids have also been determined using a thermogravimetric analysis instrument and a thermal constant analyzer, respectively. These obtained thermodynamic properties can provide crucial fundamental information for the study and application of fatty acid PCMs and related thermal energy storage techniques.

Signal of phase transition hidden in quasinormal modes of regular AdS black holes

We discuss the intrinsic relations between thermodynamic phase transitions and quasinormal modes in regular AdS black holes, specifically in the Bardeen and Hayward AdS classes. To this end, we calculate the quasinormal modes of massless scalar field perturbations around small and large black holes via the Horowitz-Hubeny method. By investigating the isobaric and isothermal phase transitions for Bardeen and Hayward AdS black holes in detail, we observe that a dramatic change of quasinormal modes appears near the phase transition point of small and large black holes, and that it corresponds to the swallow tail structure in the plane of Gibbs free energy with respect to pressure. Moreover, by analyzing the evolution of black holes along the coexistence curve of small and large black hole phases, we also observe the dramatic change in quasinormal modes. Such a phenomenon confirms the signal of the phase transition in the quasinormal mode spectrum, which can be understood as a thermodynamic signal hidden in the dynamical spectrum.

Thermodynamic phase transition and winding number for the third-order Lovelock black hole* *Supported by the National Natural Science Foundation of China (12105222, 12275216, 12247103)

Phase transition is important for understanding the nature and evolution of the black hole thermodynamic system. In this study, we predicted the phase transition of the third-order Lovelock black hole using the winding numbers in complex analysis, and qualitatively validated this prediction by the generalized free energy. For the 7<d<12-dimensional black holes in hyperbolic topology and the 7-dimensional black hole in spherical topology, the winding number obtained is three, which indicates that the system undergoes first-order and second-order phase transitions. For the 7<d<12-dimensional black holes in spherical topology, the winding number is four, and two scenarios of phase transitions exist, one involving a purely second-order phase transition and the other involving simultaneous first-order and second-order phase transitions. This result further deepens the research on black hole phase transitions using the complex analysis.

Ab initio investigation of electronic structure and magnetic transformation during the bcc to hcp transition in Fe induced by pressure

The pressure-induced structural transition from a body-centered cubic (bcc) to a hexagonal close-packed (hcp) crystal in Fe is studied through ab initio electronic structure calculations, combining with the thermodynamic and kinetic phase-transition methods. According to the energy-volume relationship and thermodynamic criterion, the reasonable phase transition pressure is calculated to be about 13.88 GPa. The SSNEB method is employed to examine kinetic structural and barrier changes along bcc-hcp transition under various pressures. The transformation path involves the deformation of (110)bcc into the tightly packed (0001)hcp, accompanied by the relative slip of (110)bcc along the [1̅10]bcc direction, leading to the formation of the hcp structure. Our results indicate a reduction in the transition barrier of bcc-hcp with increasing pressure. Under the thermodynamic phase transition pressure, the bcc-hcp phase transition barrier is still as high as 140 meV, implying that pure hydrostatic pressure is not a sufficient condition to drive the phase transition. In addition, different from the continuous change of volume, the magnetism of the structure undergoes a magnetic mutation at the transition state, and the phase transition process involves complex magnetic transitions.

Topological interpretation of extremal and Davies-type phase transitions of black holes

Topological arguments are currently being used as a novel scheme to discern the properties of black holes while ignoring their detailed structure and specific field equations. Among various avenues of black hole physics, where this novel approach is being utilized, the phase transition in black hole thermodynamics lies at the forefront. There are several types of phase transition in black holes; such as the van der Waals type phase transition, Davies-type phase transition, extremal phase transition, and Hawking-Page (HP) transition. So far, the topological interpretation, where the critical point has been identified with the non-zero topological charge, has been obtained only for the van der Waals type phase transition and HP transition in different spacetimes. To complete the picture, here we provide the same interpretation for two other phase transitions: Davies-type phase transition and extremal phase transition. The entire analysis is general and is valid for any spacetime where these types of phase transitions are observed. More importantly, our analysis suggests that amid the apparent differences in these phase transitions, they share the same topological characteristics, i.e. non-zero topological charge arising from different thermodynamic potentials in different types of phase transition.

Schwarzschild black hole surrounded by a cavity and phase transition in the non-commutative gauge theory of gravity

In this work, we investigate the phase transition of the Schwarzschild black hole (SBH) inside an isothermal spherical cavity in the context of the non-commutative (NC) gauge theory of gravity, by using the Seiberg–Witten (SW) map and the star product. Firstly, we compute the NC correction to the Hawking temperature and derive the logarithmic correction to the entropy, then we derive the local temperature and local energy of NC SBH in isothermal cavity. Our results show that the non-commutativity removes the commutative divergence behavior of temperature, and prevents the SBH from the complete evaporation, which leads to a remnant black hole, and this geometry has predicted a minimal length in the order of Planck scale Θ∼lplanck. Therefore, the thermodynamic stability and phase transition is studied by analyzing the behavior of the local heat capacity and the Helmholtz free energy in the NC spacetime, where the results show that, the NC SBH has a two second-order phase transition and one first-order phase transition, with two Hawking–Page phase transition in the NC gauge theory.

Thermodynamic signatures and phase transitions in high-energy Au–Au collision

In this study, we systematically investigate the dynamics of various hadrons namely π +, π −, K +, K −, p, p¯ , Λ, Λ¯ , Ξ− and Ξ¯+ produced in central Au–Au collisions. We analyze data of AGS and RHIC, which span a broad range of collision energies, ranging from sNN = 1.9 to 200 GeV. To analyze the transverse momentum (p T ) and transverse mass (m T ) distributions, we employ a two-component standard distribution function, achieving a very good representation of the experimental data across these energy regimes. We extract key thermodynamic parameters, including the effective temperature T, the mean transverse momentum 〈p T 〉, and the initial temperature T i , and analyze their dependence on the values of collision energy and particle mass. Our findings reveal a distinct transition behaviour around sNN=19.6GeV . Below sNN=19.6GeV , the values of T, 〈p T 〉, and T i increase monotonically for all hadrons due to higher energy transfer into the system. Above this energy threshold, these extracted parameters plateau, suggesting that the additional energy is utilized as latent heat for phase transition rather than increasing the system’s temperature. These observations delineate two distinct regions: a hadron-dominated region at lower energies and a parton-dominated region at higher energies, each potentially indicative of different phases of matter, with the latter possibly signalling the onset of a quark–gluon plasma. The study thus provides critical insights into the complex interplay of thermodynamics, phase transitions, and particle interactions in high-energy Au–Au collisions.

Thermodynamic phase transition rate for the third-order Lovelock black hole in diverse dimensions

The phase transition has always been a major focus in the study of black hole thermodynamics. This study employs the Kramer escape rate from stochastic processes to investigate the first-order phase transition strength between the large and small black hole states. The results indicate that the phase transition of the third-order Lovelock black holes exhibits significant asymmetric characteristics in diverse dimensions both in the hyperbolic and spherical topology, with an overall trend of the transition from large black holes to small black holes. Especially for the spherical topology, when the dimension is higher than seven, there exists a certain temperature beyond which a dynamic equilibrium is established for the phase transition. This study provides valuable insights into the first-order phase transition rate of black holes and enriches the understanding of black hole phase transitions.

Cosmological FLRW phase transitions and micro-structure under Kaniadakis statistics

This article studies the thermodynamics phase transitions and critical phenomena of an FLRW cosmological model under truncated Kaniadakis's statistics. The EoS is derived from the corrected Friedmann field equations and the thermodynamics unified first law. To approach thermodynamics, we use an approximation for KSAH≪1, on the cosmological equation, and also check the validity of our approximation. Then for different values from Kaniadakis parameter K, order O(10−37) for the relic-abundance, O(10−84) for 7Li-abundance and O(10−125) in the recombination era, the EoS reveals non-trivial critical points where a first-order phase transition occurs a sort of a van der Waals fluid. Interestingly, the numerical values of the critical exponents are the same as those of the van der Waals system. Besides, to obtain more insights into the thermodynamics description, the so-called Ruppeiner's geometry is studied through the normalized scalar curvature, disclosing this invariant zone where the system undergoes repulsive/attractive interactions. Near the critical point, this curvature provides again the same critical exponent and universal constant value as for van der Waals fluid. Despite the similarity, both systems are quite different because the present one considers a relativistic entropy (Kaniadakis entropy) while the Van der Waals gas responds to a classical entropy (Maxwell-Boltzmann).

Phase transition face-centered cubic crystal — homogeneous phase in helium

In this work, the characteristics of the phase transition face-centered cubic crystal — homogeneous phase in helium are calculated based on the correlation cell-cluster expansion. The theoretical data were compared with experimental data and good agreement was obtained. It is discussed the use of data on phase transitions in helium to estimate thermodynamic characteristics phase transition in a quantum system of hard spheres.

The glass transition as a boundary layer problem of the energy landscape kinetic master equations and its relationship with quantum path integrals

The glass transition is a process in which a non-periodic solid is obtained by fast cooling a melt. In this work, an analysis is made of the energy landscape kinetic equations that allow to describe such phenomena. In particular, it is shown that the glass transition occurs at the boundary layer of the energy landscape kinetic master equations, as solutions always have steep gradients and are very sensitive to the initial conditions. Moreover, it is discussed that the evolution operator is given by a path integral where the cooling rate plays a role akin to the Planck constant in a quantum mechanical problem. As an example, the kinetic equation properties of a two-level fully connected energy landscape system, capable of exhibiting both a glass and a thermodynamic phase transition, both of which are analytically solvable, are analysed in detail.

Phase transition thermodynamics of organic semiconductors: N,N,N’,N’-tetraphenylbenzidine and 4,4′-bis(N-carbazolyl)-1,1′-biphenyl

In this work, we report a comprehensive study of the phase change thermodynamics of two compounds, N,N,N’,N’-tetraphenylbenzidine (TPB) and 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), used in the production of organic light-emitting diodes and photovoltaics. The vapor pressures and phase transition enthalpies of these compounds have been previously studied at the elevated temperatures which may not be relevant to the conditions during fabrication and use TPB- and CBP-based materials. In this work, a combination of experimental and computational methods was employed to establish the reliable temperature dependences of the sublimation, fusion, and vaporization enthalpies of TPB and CBP in a wide temperature range. The vapor pressures of both compounds over solid and liquid phases were measured using fast scanning calorimetry. The fusion enthalpies at the melting point were determined by DSC. The isobaric heat capacities of the compounds in crystalline and liquid phases, including the supercooled liquids, were measured using scanning calorimetry. For the first time, the heat capacities of the ideal gas TPB and CBP were computed, considering internal rotation effects. The solution enthalpies in benzene at 298.15 K were measured, providing an independent estimate of the fusion enthalpy temperature dependence. Its consistency with the data on the fusion enthalpies was confirmed using Hess’s and Kirchhoff’s laws of Thermochemistry. Using the obtained results, the available literature data were critically evaluated. The obtained thermodynamic parameters may facilitate optimization of vapor deposition conditions and description of the thermodynamic and kinetic stability of the glassy state of TPB and CBP.

Investigation of thermodynamic state evolution, phase transition and mixing of the hydrocarbon droplet in convective supercritical environments

Liquid alkane droplets transit to supercritical fluids under supercritical conditions. However, the subsequent thermodynamic state evolution, phase transition, and mixing in this case, which directly influences combustion in actual diesel engines, need further investigation. We studied the thermodynamic state evolution, phase transition, and mixing of n-heptane droplets in supercritical laminar nitrogen streams through a set of conservation equations. Non-ideal thermodynamic and transport properties were calculated to incorporate the dramatic variation of physical properties in the supercritical regime. We focus on the effects of Reynolds number, ambient pressure, and droplet size on the thermodynamic state evolution, phase transition and mixing of droplets. Results showed that increasing the Reynolds number can accelerate the evolution of thermodynamic states, which leads to the faster transition of droplets from the liquid phase and supercritical fluids to gas-phase mixtures. With the increased Reynolds number, the phase transition rate is increased and the mixing homogeneity is improved due to the enhanced mass transfer. Caused by the negative correlation between mass transfer and ambient pressure, in higher pressure, droplets after the supercritical transition require more time to transition from supercritical fluids to vapor-phase mixtures. Increasing ambient pressure inhibited the droplet phase transition process and deteriorated the mixing homogeneity, but no significant influence was shown on the droplet dynamic evolution process. Smaller droplets transition faster from liquid phase and supercritical fluids to vapor-phase mixtures. The faster thermodynamic state evolution and faster dynamic evolution process of the smaller droplet leads to its more rapid homogeneous mixing with ambient gasses, but the mode of dynamics is independent of the droplet size.

Emergent Properties in Chemistry - Relating Molecular Properties to Bulk Behavior.

Certain properties of an object only emerge when a sufficient number of those objects are present in a definite arrangement. For example, one or two water molecules cannot said to be in a liquid state, but a drop of water can be. This concept of emergence has been studied extensively, but only occasionally discussed explicitly in the context of chemistry. In this paper, we aim to show the fruitfulness of the concept of emergence for chemical inquiry by considering four case studies of emergent chemical properties, i. e., the liquidity and freezing of water, structural properties of crystals, thermodynamical phase transitions and quantum mechanical phenomena. We show that some of these properties emerge gradually, some at discrete points, and some should be taken to emerge only when the number of constituents tends to infinity. We argue that studying the way in which chemical properties emerge presents a useful avenue for research that promises greater insight into the nature of those properties.