On the Supra‐LUMO Interaction: Case Study of a Sudden Change of Electronic Structure as a Functional Emergence

2021 ◽  
Author(s):  
Philippe Lainé ◽  
Alexis Gosset ◽  
Štěpánka Nováková Lachmanová ◽  
Sawsen Cherraben ◽  
Gildas Bertho ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Sudden Change

scholarly journals Stoichiometry and disorder influence over electronic structure in nanostructured VOx films

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
A. D’Elia ◽  
S. J. Rezvani ◽  
N. Zema ◽  
F. Zuccaro ◽  
M. Fanetti ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Distorted Octahedral Geometry ◽  
Edge Structure ◽  
Distorted Octahedral ◽  
X Ray Absorption ◽  
Complex Matter ◽  
Nanometric Size

AbstractWe present and discuss the role of nanoparticles size and stoichiometry over the local atomic environment of nanostructured VOx films. The samples have been characterized in situ using X-ray absorption near-edge structure (XANES) spectroscopy identifying the stoichiometry-dependent fingerprints of disordered atomic arrangement. In vanadium oxides, the ligand atoms arrange according to a distorted octahedral geometry depending on the oxidation state, e.g. trigonal distortion in V2O3 and tetragonal distortion in bulk VO2. We demonstrate, taking VO2 as a case study, that as a consequence of the nanometric size of the nanoparticles, the original ligands symmetry of the bulk is broken resulting in the coexistence of a continuum of distorted atomic conformations. The resulting modulation of the electronic structure of the nanostructured VOx as a function of the oxygen content reveals a stoichiometry-dependent increase of disorder in the ligands matrix. This work shows the possibility to produce VOx nanostructured films accessing new disordered phases and provides a unique tool to investigate the complex matter.

scholarly journals Atomic scale electronic structure and response in attosecond photoemission delays: A case study using non-centrosymmetric BiTeCl

2019 ◽  
Vol 205 ◽  
pp. 02016
Author(s):  
Sergej Neb ◽  
Christian Oberer ◽  
Walter Enns ◽  
Andreas Gebauer ◽  
Norbert Müller ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Atomic Scale ◽  
Time Resolved ◽  
Propagation Effects ◽  
Dynamical Screening

Attosecond time-resolved photoemission from the differently terminated BiTeCl surfaces yield a photoelectron streaking that cannot be explained by bulk propagation effects alone. Instead, the atomic scale electronic structure and dynamical screening for both surface terminations have to be taken into account.

Short-range order and its effect on the electronic structure of binary alloys: CuZn — a case study

Pramana ◽  
2008 ◽  
Vol 70 (2) ◽  
pp. 221-235 ◽  
Author(s):  
Abhijit Mookerjee ◽  
Kartick Tarafder ◽  
Atisdipankar Chakrabarti ◽  
Kamal Krishna Saha
Keyword(s):  
Electronic Structure ◽  
Short Range ◽  
Short Range Order ◽  
Binary Alloys ◽  
Range Order

scholarly journals TorsiFlex: an automatic generator of torsional conformers. Application to the twenty proteinogenic amino acids

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
David Ferro-Costas ◽  
Irea Mosquera-Lois ◽  
Antonio Fernández-Ramos
Keyword(s):  
Amino Acids ◽  
Electronic Structure ◽  
Energy Surface ◽  
Random Search ◽  
Torsional Potential ◽  
Complete Work ◽  
Chemical Knowledge ◽  
Validation Tests ◽  
User Friendly

AbstractIn this work, we introduce , a user-friendly software written in Python 3 and designed to find all the torsional conformers of flexible acyclic molecules in an automatic fashion. For the mapping of the torsional potential energy surface, the algorithm implemented in combines two searching strategies: preconditioned and stochastic. The former is a type of systematic search based on chemical knowledge and should be carried out before the stochastic (random) search. The algorithm applies several validation tests to accelerate the exploration of the torsional space. For instance, the optimized structures are stored and this information is used to prevent revisiting these points and their surroundings in future iterations. operates with a dual-level strategy by which the initial search is carried out at an inexpensive electronic structure level of theory and the located conformers are reoptimized at a higher level. Additionally, the program takes advantage of conformational enantiomerism, when possible. As a case study, and in order to exemplify the effectiveness and capabilities of this program, we have employed to locate the conformers of the twenty proteinogenic amino acids in their neutral canonical form. has produced a number of conformers that roughly doubles the amount of the most complete work to date. Graphical Abstract

scholarly journals Analysis of Cold Air Recirculation in the Evaporators of Large-Scale Air-Source Heat Pumps Using CFD Simulations

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 186
Author(s):  
Brice Rogié ◽  
Jonas Kjær Jensen ◽  
Svenn Ole Kjøller Hansen ◽  
Wiebke Brix Markussen
Keyword(s):  
Heat Pump ◽  
Large Scale ◽  
Sudden Change ◽  
District Heating ◽  
Heat Pumps ◽  
Cfd Model ◽  
Additional Energy ◽  
Cold Air ◽  
Air Source Heat Pump

The present study investigates cold air recirculation in the evaporators of large-scale air-source heat pumps. A case study considered a 5 MW air-source heat pump producing heat for district heating. The heat pump comprises 20 horizontal evaporators, where each evaporator is equipped with eight fans. The evaporators were implemented in a CFD model, where the influence of the outdoor wind direction on the recirculation was investigated. Firstly, the air recirculation was analysed with no surrounding obstacles. Secondly, the surrounding building and the real ground topology was included in the CFD model, to analyse their influence on the air recirculation. The results show that recirculation occurs for all wind directions, due to the turbulent behaviour of the flow around the evaporators. The results also show that the presence of a building intensifies the recirculation when it is placed directly upstream of the evaporators due to the presence of vortices in the wake of the building. On the other hand, a ground depression helps to reduce the recirculation by having additional energy dissipation due to the sudden change in the ground direction.

Active Learning of Many-Body Configuration Space: Application to the Cs+–water MB-nrg Potential Energy Function as a Case Study

2020 ◽  
Author(s):  
Yaoguang Zhai ◽  
Alessandro Caruso ◽  
Sicun Gao ◽  
Francesco Paesani
Keyword(s):  
Electronic Structure ◽  
Active Learning ◽  
Potential Energy ◽  
Molecular Simulations ◽  
Electronic Structure Calculations ◽  
Many Body ◽  
High Level ◽  
Structure Calculations ◽  
Training Sets

<div> <div> <div> <p>The efficient selection of representative configurations that are used in high-level electronic structure calculations needed for the development of many-body molecular models poses a challenge to current data-driven approaches to molecular simulations. Here, we introduce an active learning (AL) framework for generating training sets corresponding to individual many-body contributions to the energy of a N-body system, which are required for the development of MB-nrg potential energy functions (PEFs). Our AL framework is based on uncertainty and error estimation, and uses Gaussian process regression (GPR) to identify the most relevant configurations that are needed for an accurate representation of the energy landscape of the molecular system under exam. Taking the Cs<sup>+</sup>–water system as a case study, we demonstrate that the application of our AL framework results in significantly smaller training sets than previously used in the development of the original MB-nrg PEF, without loss of accuracy. Considering the computational cost associated with high-level electronic structure calculations for training set configurations, our AL framework is particularly well-suited to the development of many-body PEFs, with chemical and spectroscopic accuracy, for molecular simulations from the gas to condensed phase. </p> </div> </div> </div>

scholarly journals Inclusion of Relativistic Effects in Electronic Structure Calculations

1986 ◽  
Vol 39 (5) ◽  
pp. 667 ◽  
Author(s):  
KG Dyall
Keyword(s):  
Molecular Structure ◽  
Electronic Structure ◽  
Dirac Equation ◽  
Atomic Number ◽  
Perturbation Methods ◽  
Relativistic Effects ◽  
Electronic Structure Calculations ◽  
Variational Treatment ◽  
Structure Calculations

The effects of relativity on atomic and molecular structure are discussed with an indication of their importance as a function of atomic number. Perturbation methods for the inclusion of relativistic effects are briefly analysed in terms of the Dirac equation; the multi-configuration Dirac-Fock method for the variational treatment of relativistic effects is then discussed in more detail. Finally, a case study on 2p ionisation in Ca is presented, in which higher-order relativistic effects are important.

scholarly journals Managing risks of precast concrete supply chain: a case study

2019 ◽  
Vol 270 ◽  
pp. 05004
Author(s):  
Jati Utomo Dwi Hatmoko ◽  
Mochamad Agung Wibowo ◽  
Marita Dewi Astuty ◽  
Desy Ratna Arthaningtyas ◽  
Moh Nur Sholeh
Keyword(s):  
Supply Chain ◽  
Precast Concrete ◽  
Sudden Change ◽  
Production Capacity ◽  
Mitigation Strategies ◽  
Natural Material ◽  
Skilled Workers ◽  
Five Dimensions ◽  
Four Levels

Precast concrete has typically long lead time, starting from order placement, production stage, to delivery to project site, all of which requires good supply chain management. As a consequence, the risks of its supply chains are inevitable and must be anticipated to ensure the success of a project. The aim of this research is to assess the risks of the supply chain of precast concrete from production to delivery to projects. WKB, a government-owned company that produces precast concrete, has been used as the case study. Activities along the supply chain were mapped based on five dimensions of Supply Chain Operation Reference (SCOR), i.e. Plan – Source – Make – Deliver – Return, upon which risks were identified. Data was collected through in-depth interview and questionnaire survey to key persons of WKB. A 1-5 Likert scale was used to quantify the occurrence and severity of risks along the supply chain. The identified risks were classified into four levels based on the multiplication of the occurrence and the severity, i.e. critical, major, moderate, and minor. A total of nine critical risks were found along the supply chain, i.e. sales forecast and planning for production (Plan); production capacity of natural material vendors (Source); sudden change of production, shortage of skilled workers, additional cost for land stockyard rental, and renewal for industrial land lease license (Make); risk of non-standard transportation (Deliver); defective and failed products (Return). This research provides a valuable understanding of the risks of the precast concrete supply chain and the mitigation strategies.

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