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As recently proposed, the long-time behavior of equilibrium time-correlation functions for one-dimensional systems are expected to be captured by a nonlinear extension of fluctuating hydrodynamics. We outline the predictions from the theory aimed at the comparison with molecular dynamics. We report on numerical simulations of a fluid with a hard-shoulder potential and of a hard-point gas with alternating masses. These models have in common that the collision time is zero and their dynamics amounts to iterating collision by collision. The theory is well confirmed, with the twist that the nonuniversal coefficients are still changing at longest accessible times.
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http://dx.doi.org/10.1103/PhysRevE.90.012147 | DOI Listing |
J Phys Chem B
July 2025
Department of Biochemistry and Molecular Biology, Department of Chemistry, The University of Chicago, 5735 S Ellis Ave., Chicago, Illinois 60637, United States.
A computational framework for rigorously computing the membrane permeability of small molecules from unbiased molecular dynamics simulations is presented. The method in its optimized form exploits the committor probability within the transition path theory framework and is applicable to molecules with free energy barriers for which a determination of the permeability coefficient from spontaneous crossings during equilibrium simulations would be unfeasible. A novel computational protocol is implemented through which the equilibrium time-correlation function is calculated from a combination of enhanced sampling to determine the equilibrium potential of mean force of the permeant molecule and a reweighted ensemble of short unbiased trajectories.
View Article and Find Full Text PDFEntropy (Basel)
April 2025
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, I-40127 Bologna, Italy.
Quantum computing gives direct access to the study of the real-time dynamics of quantum many-body systems. In principle, it is possible to directly calculate non-equal-time correlation functions, from which one can detect interesting phenomena, such as the presence of quantum scars or dynamical quantum phase transitions. In practice, these calculations are strongly affected by noise, due to the complexity of the required quantum circuits.
View Article and Find Full Text PDFPhys Rev E
March 2025
The University of Tokyo, Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, Kashiwa 277-8561, Japan.
Geometrical methods are extensively applied to thermodynamics, including stochastic thermodynamics. In the case of a slow-driving linear response regime, a geometrical framework, known as thermodynamic geometry, is established. The key to this framework is the thermodynamic length characterized by a metric tensor defined in the space of controlling variables.
View Article and Find Full Text PDFPhys Rev E
March 2025
Universidad Politécnica de Querétaro, El Marqués, 76240 Querétaro, Mexico.
We study the influence of thermal fluctuations on the two-time correlation functions of bosonic baths within a superstatistics framework by assuming that fluctuations follow the gamma distribution. We further establish a connection between superstatistics and Tsallis nonadditive thermodynamics by introducing a temperature-renormalizing parameter. Our results show that, for an Ohmic model, the system's correlation functions exhibit diverse time-dependent behaviors, with the real and imaginary parts displaying enhancement or suppression depending on temperature and fluctuation strength.
View Article and Find Full Text PDFPhys Rev E
March 2025
KU Leuven, Department of Physics and Astronomy, 3000, Belgium.
Using a powerful combination of projection-operator method and path-space response theory, we derive the fluctuation dynamics of a slow inertial probe coupled to a steady nonequilibrium medium under the assumption of time-scale separation. The nonequilibrium is realized by external nongradient driving on the medium particles or by their (athermal) active self-propulsion. The resulting friction on the probe is an explicit time correlation for medium observables and is decomposed into two terms: one entropic, proportional to the noise variance as in the Einstein relation for equilibrium media, and a frenetic term that can take both signs.
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