Publications de Wencheng Ji | EPFL Graph Search

Local vs. cooperative: Unraveling glass transition mechanisms with SEER

Which phenomenon slows down the dynamics in supercooled liquids and turns them into glasses is a long-standing question of condensed matter. Most popular theories posit that as the temperature decreases, many events must occur in a coordinated fashion on a ...

National Academy of Sciences2024

Scaling Description of Creep Flow in Amorphous Solids

Matthieu Wyart, Thomas Willem Jan de Geus, Wencheng Ji, Marko Popovic

Amorphous solids such as coffee foam, toothpaste, or mayonnaise display a transient creep flow when a stress E is suddenly imposed. The associated strain rate is commonly found to decay in time as gamma_ -t-nu, followed either by arrest or by a sudden flui ...

AMER PHYSICAL SOC2022

Mean-field description for the architecture of low-energy excitations in glasses

Matthieu Wyart, Thomas Willem Jan de Geus, Elisabeth Agoritsas, Wencheng Ji

In amorphous materials, groups of particles can rearrange locally into a new stable configuration. Such elementary excitations are key as they determine the response to external stresses, as well as to thermal and quantum fluctuations. Yet, understanding w ...

2022

Thermally activated flow in models of amorphous solids

Matthieu Wyart, Thomas Willem Jan de Geus, Wencheng Ji, Marko Popovic

Amorphous solids yield at a critical value Sigma(c) of the imposed stress Sigma through a dynamical phase transition. While sharp in athermal systems, the presence of thermal fluctuations leads to the rounding of the transition and thermally activated flow ...

AMER PHYSICAL SOC2021

Local excitations in amorphous solids

Wencheng Ji

Amorphous solids are structurally disordered. They are very common and include glasses, colloids, and granular materials, but are far less understood than crystalline solids. Key aspects of these materials are controlled by the presence of excitations in w ...

EPFL2021

Thermal origin of quasilocalized excitations in glasses

Matthieu Wyart, Thomas Willem Jan de Geus, Elisabeth Agoritsas, Wencheng Ji, Marko Popovic

Key aspects of glasses are controlled by the presence of excitations in which a group of particles can rearrange. Surprisingly, recent observations indicate that their density is dramatically reduced and their size decreases as the temperature of the super ...

2020

How collective asperity detachments nucleate slip at frictional interfaces

Matthieu Wyart, Thomas Willem Jan de Geus, Wencheng Ji, Marko Popovic

Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes ...

National Academy of Sciences2019

Fast generation of ultrastable computer glasses by minimization of an augmented potential energy

Matthieu Wyart, Wencheng Ji, Carolina Brito Carvalho dos Santos

We present a model and protocol that enable the generation of extremely stable computer glasses at minimal computational cost. The protocol consists of an instantaneous quench in an augmented potential energy landscape, with particle radii as additional de ...

AMER PHYSICAL SOC2019

Theory for the density of interacting quasilocalized modes in amorphous solids

Matthieu Wyart, Thomas Willem Jan de Geus, Wencheng Ji, Marko Popovic

Quasilocalized modes appear in the vibrational spectrum of amorphous solids at low frequency. Though never formalized, these modes are believed to have a close relationship with other important local excitations, including shear transformations and two-lev ...

AMER PHYSICAL SOC2019