2022 New's Items

Coupled charge and energy transfer dynamics in light harvesting complexes from a hybrid hierarchical equations of motion approach

Fay TP
Limmer DT
2022

We describe a method for simulating exciton dynamics in protein–pigment complexes, including effects from charge transfer as well as fluorescence. The method combines the hierarchical equations of motion, which are used to describe quantum dynamics of excitons, and the Nakajima–Zwanzig quantum master equation, which is used to describe slower charge transfer processes. We study the charge transfer quenching in light harvesting complex II, a protein postulated to control non-photochemical quenching in many plant species. Using our hybrid approach, we find good agreement between our...

Kinetic frustration by limited bond availability controls the LAT protein condensation phase transition on membranes

Sun S
GrandPre T
Limmer DT
Groves JT
2022

LAT is a membrane-linked scaffold protein that undergoes a phase transition to form a two-dimensional protein condensate on the membrane during T cell activation. Governed by tyrosine phosphorylation, LAT recruits various proteins that ultimately enable condensation through a percolation network of discrete and selective protein-protein interactions. Here, we describe detailed kinetic measurements of the phase transition, along with coarse-grained model simulations, that reveal that LAT condensation is kinetically frustrated by the availability of bonds to form the network. Unlike...

Nonadiabatic transition paths from quantum jump trajectories

Anderson MC
Schile AJ
Limmer DT
2022

We present a means of studying rare reactive pathways in open quantum systems using transition path theory and ensembles of quantum jump trajectories. This approach allows for the elucidation of reactive paths for dissipative, nonadiabatic dynamics when the system is embedded in a Markovian environment. We detail the dominant pathways and rates of thermally activated processes and the relaxation pathways and photoyields following vertical excitation in a minimal model of a conical intersection. We find that the geometry of the conical intersection affects the electronic character of...

Temperature Dependence of the Relative Rates of Chlorination and Hydrolysis of N2O5 in NaCl-Water Solutions.

Kegel S
Derrah TF
Moon SJ
Limmer DT
Nathanson GM
Bertram TH
2022

We have measured the temperature dependence of the ClNO<sub>2</sub> product yield in competition with hydrolysis following N<sub>2</sub>O<sub>5</sub> uptake to aqueous NaCl solutions. For NaCl-D<sub>2</sub>O solutions spanning 0.0054 M to 0.21 M, the ClNO<sub>2</sub> product yield decreases on average by only 43 % from 5 to 25 C. Less reproducible measurements at 0.54 M and 2.4 M NaCl also fall within this range. The ratio of the rate constants for chlorination and hydrolysis of N<sub>2</sub>O<sub>5</sub...

Renormalization of excitonic properties by polar phonons

Park Y
Limmer DT
2022

We employ quasiparticle path integral molecular dynamics to study how the excitonic properties of model semiconductors are altered by electron–phonon coupling. We describe ways within a path integral representation of the system to evaluate the renormalized mass, binding energy, and radiative recombination rate of excitons in the presence of a fluctuating lattice. To illustrate this approach, we consider Fröhlich-type electron–phonon interactions and employ an imaginary time influence functional to incorporate phonon-induced effects nonperturbatively. The effective mass and binding...

Xanthophyll-cycle based model of the rapid photoprotection of Nannochloropsis in response to regular and irregular light/dark sequences

Short AH
Fay TP
Crisanto T
Hall J
Steen CJ
Niyogi KK
Limmer DT
Fleming G
2022

We explore the photoprotection dynamics of Nannochloropsis oceanica using time-correlated single photon counting under regular and irregular actinic light sequences. The varying light sequences mimic natural conditions, allowing us to probe the real-time response of non-photochemical quenching (NPQ) pathways. Durations of fluctuating light exposure during a fixed total experimental time and prior light exposure of the algae are both found to have a profound effect on NPQ. These observations are rationalized with a quantitative model based on the xanthophyll cycle and the...

Defect-mediated ripening of core-shell nanostructures

Zhang Q
Peng X
Nie Y
Wang L
Limmer DT
Zheng H
2022

Understanding nanostructure ripening mechanisms is desirable for gaining insight on the growth and potential applications of nanoscale materials. However, the atomic pathways of nanostructure ripening in solution have rarely been observed directly. Here, we report defect-mediated ripening of Cd-CdCl2 core-shell nanoparticles (CSN) revealed by in-situ atomic resolution imaging with liquid cell transmission electron microscopy. We find that ripening is initiated by dissolution of the nanoparticle with an incomplete CdCl2 shell, and...

Self-assembly of nanocrystals into strongly electronically coupled all-inorganic supercrystals

Coropceanu I
Janke EM
Limmer DT
de la Cruz MO
Ginsberg NS
Talapin DV
2022

Colloidal nanocrystals of metals, semiconductors, and other functional materials can self-assemble into long-range ordered crystalline and quasicrystalline phases, but insulating organic surface ligands prevent the development of collective electronic states in ordered nanocrystal assemblies. We reversibly self-assembled colloidal nanocrystals of gold, platinum, nickel, lead sulfide, and lead selenide with conductive inorganic ligands into supercrystals exhibiting optical and electronic properties consistent with strong electronic coupling between the constituent nanocrystals. The...

Uptake of N2O5 by aqueous aerosol unveiled using chemically accurate many-body potentials

Cruzeiro VWD
Galib M
Limmer DT
Götz AW
2022

The reactive uptake of N2O5 to aqueous aerosol is a major loss channel for nitrogen oxides in the troposphere. Despite its importance, a quantitative picture of the uptake mechanism is missing. Here we use molecular dynamics simulations with a data-driven many-body model of coupled-cluster accuracy to quantify thermodynamics and kinetics of solvation and adsorption of N2O5 in water. The free energy profile highlights that N2O5 is...

Nonlocal Screening Dictates the Radiative Lifetimes of Excitations in Lead Halide Perovskites

Park Y
Obliger A
Limmer DT
2022

We use path integral molecular dynamics simulations and theory to elucidate the interactions between charge carriers, as mediated by a lead halide perovskite lattice. We find that the charge–lattice coupling of MAPbI3 results in a repulsive interaction between electrons and holes at intermediate distances. The effective interaction is understood using a Gaussian field theory, whereby the underlying soft, polar lattice contributes a nonlocal screening between quasiparticles. Path integral calculations of this nonlocal screening model are used to rationalize...