CHARACTERIZATIONS OF FAR FROM EQUILIBRIUM STRUCTURES USING THEIR CONTOURS

2004 ◽  
pp. 319-328
Author(s):  
Girish Nathan ◽  
Gemunu H. Gunaratne
Keyword(s):  
Equilibrium Structures ◽  
Far From Equilibrium

scholarly journals Real-time dynamics and structures of supported subnanometer catalysts via multiscale simulations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yifan Wang ◽  
Jake Kalscheur ◽  
Ya-Qiong Su ◽  
Emiel J. M. Hensen ◽  
Dionisios G. Vlachos
Keyword(s):  
Co Adsorption ◽  
Metastable Equilibrium ◽  
Modeling Framework ◽  
Time Dynamics ◽  
Structure Changes ◽  
Rapid Sintering ◽  
Equilibrium Structures ◽  
Far From Equilibrium ◽  
Multiscale Modeling Framework ◽  
Spectroscopic Probe

AbstractUnderstanding the performance of subnanometer catalysts and how catalyst treatment and exposure to spectroscopic probe molecules change the structure requires accurate structure determination under working conditions. Experiments lack simultaneous temporal and spatial resolution and could alter the structure, and similar challenges hinder first-principles calculations from answering these questions. Here, we introduce a multiscale modeling framework to follow the evolution of subnanometer clusters at experimentally relevant time scales. We demonstrate its feasibility on Pd adsorbed on CeO2(111) at various catalyst loadings, temperatures, and exposures to CO. We show that sintering occurs in seconds even at room temperature and is mainly driven by free energy reduction. It leads to a kinetically (far from equilibrium) frozen ensemble of quasi-two-dimensional structures that CO chemisorption and infrared experiments probe. CO adsorption makes structures flatter and smaller. High temperatures drive very rapid sintering toward larger, stable/metastable equilibrium structures, where CO induces secondary structure changes only.

BAND NN: A Deep Learning Framework For Energy Prediction and Geometry Optimization of Organic Small Molecules

2019 ◽  
Author(s):  
Siddhartha Laghuvarapu ◽  
Yashaswi Pathak ◽  
U. Deva Priyakumar
Keyword(s):  
Machine Learning ◽  
Density Functional ◽  
Computational Cost ◽  
Geometry Optimization ◽  
Dft Methods ◽  
Energy Prediction ◽  
Machine Learning Model ◽  
Equilibrium Structures ◽  
High Level ◽  
Non Equilibrium

Recent advances in artificial intelligence along with development of large datasets of energies calculated using quantum mechanical (QM)/density functional theory (DFT) methods have enabled prediction of accurate molecular energies at reasonably low computational cost. However, machine learning models that have been reported so far requires the atomic positions obtained from geometry optimizations using high level QM/DFT methods as input in order to predict the energies, and do not allow for geometry optimization. In this paper, a transferable and molecule-size independent machine learning model (BAND NN) based on a chemically intuitive representation inspired by molecular mechanics force fields is presented. The model predicts the atomization energies of equilibrium and non-equilibrium structures as sum of energy contributions from bonds (B), angles (A), nonbonds (N) and dihedrals (D) at remarkable accuracy. The robustness of the proposed model is further validated by calculations that span over the conformational, configurational and reaction space. The transferability of this model on systems larger than the ones in the dataset is demonstrated by performing calculations on select large molecules. Importantly, employing the BAND NN model, it is possible to perform geometry optimizations starting from non-equilibrium structures along with predicting their energies.

scholarly journals Tunable thermo-reversible bicontinuous nanoparticle gel driven by the binary solvent segregation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuyin Xi ◽  
Ronald S. Lankone ◽  
Li-Piin Sung ◽  
Yun Liu
Keyword(s):  
Phase Separation ◽  
Domain Size ◽  
Binary Solvent ◽  
Colloidal Systems ◽  
Colloidal Assembly ◽  
Structures And Properties ◽  
Wide Range ◽  
Equilibrium Process ◽  
Equilibrium Structures ◽  
Non Equilibrium

AbstractBicontinuous porous structures through colloidal assembly realized by non-equilibrium process is crucial to various applications, including water treatment, catalysis and energy storage. However, as non-equilibrium structures are process-dependent, it is very challenging to simultaneously achieve reversibility, reproducibility, scalability, and tunability over material structures and properties. Here, a novel solvent segregation driven gel (SeedGel) is proposed and demonstrated to arrest bicontinuous structures with excellent thermal structural reversibility and reproducibility, tunable domain size, adjustable gel transition temperature, and amazing optical properties. It is achieved by trapping nanoparticles into one of the solvent domains upon the phase separation of the binary solvent. Due to the universality of the solvent driven particle phase separation, SeedGel is thus potentially a generic method for a wide range of colloidal systems.

scholarly journals Handhold-Mediated Strand Displacement: A Nucleic Acid Based Mechanism for Generating Far-from-Equilibrium Assemblies through Templated Reactions

ACS Nano ◽  
2021 ◽  
Vol 15 (2) ◽  
pp. 3272-3283
Author(s):  
Javier Cabello-Garcia ◽  
Wooli Bae ◽  
Guy-Bart V. Stan ◽  
Thomas E. Ouldridge
Keyword(s):  
Nucleic Acid ◽  
Strand Displacement ◽  
Far From Equilibrium

scholarly journals Far-from-equilibrium initial conditions probed by a nonlocal observable

2017 ◽  
Vol 773 ◽  
pp. 91-97 ◽  
Author(s):  
L. Shahkarami ◽  
H. Ebrahim ◽  
M. Ali-Akbari ◽  
F. Charmchi
Keyword(s):  
Initial Conditions ◽  
Far From Equilibrium

scholarly journals How accurate is the determination of equilibrium structures for van der Waals complexes? The dimer N2O⋯CO as an example

2021 ◽  
Vol 154 (19) ◽  
pp. 194302
Author(s):  
Jean Demaison ◽  
Natalja Vogt ◽  
Yan Jin ◽  
Rizalina Tama Saragi ◽  
Marcos Juanes ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Complexes ◽  
Equilibrium Structures

scholarly journals Femtosecond control of phonon dynamics near a magnetic order critical point

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
O. Yu. Gorobtsov ◽  
L. Ponet ◽  
S. K. K. Patel ◽  
N. Hua ◽  
A. G. Shabalin ◽  
...  
Keyword(s):  
Critical Point ◽  
Landau Theory ◽  
Density Wave ◽  
Spin Density Wave ◽  
Vibrational States ◽  
Spin Order ◽  
Lattice Displacement ◽  
Far From Equilibrium ◽  
Crystalline System ◽  
Dynamical Control

AbstractThe spin-phonon interaction in spin density wave (SDW) systems often determines the free energy landscape that drives the evolution of the system. When a passing energy flux, such as photoexcitation, drives a crystalline system far from equilibrium, the resulting lattice displacement generates transient vibrational states. Manipulating intermediate vibrational states in the vicinity of the critical point, where the SDW order parameter changes dramatically, would then allow dynamical control over functional properties. Here we combine double photoexcitation with an X-ray free-electron laser (XFEL) probe to control and detect the lifetime and magnitude of the intermediate vibrational state near the critical point of the SDW in chromium. We apply Landau theory to identify the mechanism of control as a repeated partial quench and sub picosecond recovery of the SDW. Our results showcase the capabilities to influence and monitor quantum states by combining multiple optical photoexcitations with an XFEL probe. They open new avenues for manipulating and researching the behaviour of photoexcited states in charge and spin order systems near the critical point.

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