Using hybrid molecular dynamics/SWAP Monte Carlo (MD/SMC) simulations, we show that while the terminal relaxation times τ(ϕ) for FIRE energy minimization of soft-sphere glasses can decrease by orders of magnitude as sample equilibration proceeds and the jamming density ϕ_{J} increases, they always scale as τ(ϕ)∼(ϕ_{J}-ϕ)^{-2}∼[Z_{iso}-Z_{ms}(τ)]^{-2}, where Z_{iso}=2d and Z_{ms}(τ) is the average coordination number of particles satisfying a minimal local mechanical stability criterion (Z≥d+1) at the top of the final potential-energy-landscape (PEL) sub-basin the system encounters. This scaling allows us to collapse τ datasets that look very different when plotted as a function of ϕ, and to address a closely related question: how does the character of the PEL basins that dense thermal glasses most typically occupy evolve as the glasses age at constant ϕ and T?
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http://dx.doi.org/10.1103/PhysRevE.109.L062603 | DOI Listing |
J Chem Phys
August 2024
Dipartimento di Fisica, Università di Trieste, Strada Costiera 11, 34151 Trieste, Italy.
Policy-guided Monte Carlo is an adaptive method to simulate classical interacting systems. It adjusts the proposal distribution of the Metropolis-Hastings algorithm to maximize the sampling efficiency, using a formalism inspired by reinforcement learning. In this work, we first extend the policy-guided method to deal with a general state space, comprising, for instance, both discrete and continuous degrees of freedom, and then apply it to a few paradigmatic models of glass-forming mixtures.
View Article and Find Full Text PDFPhys Rev E
June 2024
Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
Using hybrid molecular dynamics/SWAP Monte Carlo (MD/SMC) simulations, we show that while the terminal relaxation times τ(ϕ) for FIRE energy minimization of soft-sphere glasses can decrease by orders of magnitude as sample equilibration proceeds and the jamming density ϕ_{J} increases, they always scale as τ(ϕ)∼(ϕ_{J}-ϕ)^{-2}∼[Z_{iso}-Z_{ms}(τ)]^{-2}, where Z_{iso}=2d and Z_{ms}(τ) is the average coordination number of particles satisfying a minimal local mechanical stability criterion (Z≥d+1) at the top of the final potential-energy-landscape (PEL) sub-basin the system encounters. This scaling allows us to collapse τ datasets that look very different when plotted as a function of ϕ, and to address a closely related question: how does the character of the PEL basins that dense thermal glasses most typically occupy evolve as the glasses age at constant ϕ and T?
View Article and Find Full Text PDFPhys Rev Lett
October 2023
Theoretical Sciences Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, 560064 Bengaluru, India.
We investigate the dynamics of soft sphere liquids through computer simulations for spatial dimensions from d=3 to 8, over a wide range of temperatures and densities. Employing a scaling of density-temperature-dependent relaxation times, we precisely identify the density ϕ_{0}, which marks the ideal glass transition in the hard sphere limit, and a crossover from sub- to super-Arrhenius temperature dependence. The difference between ϕ_{0} and the athermal jamming density ϕ_{J}, small in 3 and 4 dimensions, increases with dimension, with ϕ_{0}>ϕ_{J} for d>4.
View Article and Find Full Text PDFJ Chem Phys
December 2022
Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, 72570 Puebla, Mexico.
We investigate the structural relaxation of a soft-sphere liquid quenched isochorically (ϕ = 0.7) and instantaneously to different temperatures T above and below the glass transition. For this, we combine extensive Brownian dynamics simulations and theoretical calculations based on the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2022
Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, I-00161 Roma, Italy;
We study the instantaneous normal mode (INM) spectrum of a simulated soft-sphere liquid at different equilibrium temperatures We find that the spectrum of eigenvalues [Formula: see text] has a sharp maximum near (but not at) [Formula: see text] and decreases monotonically with [Formula: see text] on both the stable and unstable sides of the spectrum. The spectral shape strongly depends on temperature. It is rather asymmetric at low temperatures (close to the dynamical critical temperature) and becomes symmetric at high temperatures.
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