2021 New's Items

Visualizing electron localization of WS2/WSe2 moiré superlattices in momentum space

Stansbury CH
Utama MIB
Fatuzzo CG
Regan EX
Wang D
Xiang Z
Ding M
Watanabe K
Taniguchi T
Blei M
Shen Y
Lorcy S
Bostwick A
Jozwiak C
Koch R
Tongay S
Avila J
Rotenberg E
Wang F
Lanzara A
2021

The search for materials with flat electronic bands continues due to their potential to drive strong correlation and symmetry breaking orders. Electronic moirés formed in van der Waals heterostructures have proved to be an ideal platform. However, there is no holistic experimental picture for how superlattices modify electronic structure. By combining spatially resolved angle-resolved photoemission spectroscopy with optical spectroscopy, we report the first direct evidence of how strongly correlated phases evolve from a weakly interacting regime in a transition metal dichalcogenide...

Variational design principles for nonequilibrium colloidal assembly

Das A
Limmer DT
2021

Using large deviation theory and principles of stochastic optimal control, we show that rare molecular dynamics trajectories conditioned on assembling a specific target structure encode a set of interactions and external forces that lead to enhanced stability of that structure. Such a relationship can be formulated into a variational principle, for which we have developed an associated optimization algorithm and have used it to determine optimal forces for targeted self-assembly within nonequilibrium steady-states. We illustrate this perspective on inverse design in a model of...

Entropy production fluctuations encode collective behavior in active matter

2021

We derive a general lower bound on distributions of entropy production in interacting active matter systems. The bound is tight in the limit that interparticle correlations are small and short-ranged, which we explore in four canonical active matter models. In all models studied, the bound is weak where collective fluctuations result in long-ranged correlations, which subsequently links the locations of phase transitions to enhanced entropy production fluctuations. We develop a theory for the onset of enhanced fluctuations and relate it to specific phase transitions in active...

Ion Dissociation Dynamics in an Aqueous Premelting Layer

Niblett SP
Limmer DT
2021

Using molecular dynamics simulations and methods of importance sampling, we study the thermodynamics and dynamics of sodium chloride in the aqueous premelting layer formed spontaneously at the interface between ice and its vapor. We uncover a hierarchy of time scales that characterize the relaxation dynamics of this system, spanning the picoseconds of ionic motion to the tens or hundreds of nanoseconds associated with fluctuations of the liquid–crystal interface in their presence. We find that ions distort both local interfaces, incurring restoring forces that result in the ions...

Dissipation bounds the amplification of transition rates far from equilibrium

2021

Complex systems can convert energy imparted by nonequilibrium forces to regulate how quickly they transition between long-lived states. While such behavior is ubiquitous in natural and synthetic systems, currently there is no general framework to relate the enhancement of a transition rate to the energy dissipated or to bound the enhancement achievable for a given energy expenditure. We employ recent advances in stochastic thermodynamics to build such a framework, which can be used to gain mechanistic insight into transitions far from equilibrium. We show that under general...

Reactive uptake of N2O5 by atmospheric aerosol is dominated by interfacial processes

Galib M
Limmer DT
2021

Nitrogen oxides are removed from the troposphere through the reactive uptake of N2O5 into aqueous aerosol. This process is thought to occur within the bulk of an aerosol, through solvation and subsequent hydrolysis. However, this perspective is difficult to reconcile with field measurements and cannot be verified directly because of the fast reaction kinetics of N2O5. Here, we use molecular simulations, including reactive potentials and importance sampling, to study the uptake of N...

Response theory for nonequilibrium steady states of open quantum systems

Levy A
Rabani E
Limmer DT
2021

We introduce a response theory for open quantum systems within nonequilibrium steady states subject to a Hamiltonian perturbation. Working in the weak system-bath coupling regime, our results are derived within the Lindblad-Gorini-Kossakowski-Sudarshan formalism. We find that the response of the system to a small perturbation is not simply related to a correlation function within the system, unlike traditional linear response theory in closed systems or expectations from the fluctuation-dissipation theorem. In limiting cases, when the perturbation is small relative to the coupling to...

Insights Into the Uptake of N2O5 by Aqueous Aerosol Using Chemically Accurate Many-Body Potentials

Cruzeiro VWD
Galib M
Limmer DT
Goetz AW
2021

We study the uptake of N2O5 into pure water using molecular dynamics simulations performed with a recently developed, data driven MB-nrg model. Our model follows the same basis of the MB-pol water many body model and has coupled-cluster accuracy. We quantify the thermodynamics of solvation and adsorption using enhanced sampling techniques and free energy calculations. The free energy profile obtained highlights that N2O5 is selectively adsorbed to the liquid-vapor interface and weakly solvated. We further find that accommodation into the bulk solution occurs rather slowly, and...

Molecular Properties and Chemical Transformations Near Interfaces

Ahmed M
Blum M
Crumlin EJ
Geissler PL
Head-Gordon T
Limmer DT
Mandadapu KK
Saykally RJ
Wilson KR
2021

The properties of bulk water and aqueous solutions are known to change in the vicinity of an interface and/or in a confined environment, including the thermodynamics of ion selectivity at interfaces, transition states and pathways of chemical reactions, and nucleation events and phase growth. Here we describe joint progress in identifying unifying concepts about how air, liquid, and solid interfaces can alter molecular properties and chemical reactivity compared to bulk water and multicomponent solutions. We also discuss progress made in interfacial chemistry through advancements in...

Principles of low dissipation computing from a stochastic circuit model

Gao CY
Limmer DT
2021

We introduce a thermodynamically consistent, minimal stochastic model for complementary logic gates built with field-effect transistors. We characterize the performance of such gates with tools from information theory and study the interplay between accuracy, speed, and dissipation of computations. With a few universal building blocks, such as the not and nand gates, we are able to model arbitrary combinatorial and sequential logic circuits, which are modularized to implement computing tasks. We find generically that high accuracy...