Download Free Development And Applications Of Variable Charge Reactive Potentials For The Atomistic Simulations Of Heterogeneous Interfaces Book in PDF and EPUB Free Download. You can read online Development And Applications Of Variable Charge Reactive Potentials For The Atomistic Simulations Of Heterogeneous Interfaces and write the review.

ABSTRACT: Electronic devices, gas sensors, micro- and nano- electromechanical systems and catalytic devices are usually composed of multifunctional nano-scaled structures. Inherent to these complex nanostructures are heterogeneous interfaces such as, for example, metal/metal oxide, semiconductor/metal oxide, and metal oxide/gaseous molecule interfaces. These heterogeneous interfaces play a crucial role in the applications of nanostructures. With recent advancements in technology, these nanostructures have shrunk to dimensions less than tens of nanometers and contain less than hundreds of billions of atoms. It has also recently become routine to model and simulate these multi-million-atom nanostructures with heterogeneous interfaces at the atomistic level using molecular dynamics (MD) simulations. The capability to simulate atoms interacting with each other in these multifunctional nanostructures has made probing, understanding and engineering the atomic-level properties of materials possible.
Molecular dynamics simulations of the oxidation of the Cu (100) surface using the COMB potential reveal a fairly low occurrence of reactions. Single point calculations of O2 on this surface predict that molecular dissociation only occurs when both O atoms are close to adjacent four fold hollow sites. The molecule dissociates to form a c(2x2) surface at low temperature and low oxygen coverage. At room temperature and with higher coverage, the surface reconstructs to a missing row (squared root of 2 \U+00d7\ 2 squared root of 2)R45° configuration. These findings are consistent with experimental observations.
The depletion of fossil fuels necessitates alternate and clean energy sources. Lithium-ion batteries and solid oxide electrocatalysis devices are some of the most popular candidates. However, further improvements of these energy storage devices are essential in order to meet the ever-increasing global energy demand. Improvement of the performance of these high energy chemical systems is directly linked to the understanding and improving the complex physical and chemical phenomena and exchanges that take place at their different interfaces. Surfaces or interfaces, structures created between dissimilar media, such as liquids and solids, and interphases, structures arising in between these dissimilar media, present great challenges for their study and understanding since these are the regions where myriad events such as electron transfer, ion transfer and migration, reactions, and solvation/desolvation processes take place and significantly alter their landscape. In order to investigate the physical and chemical interactions at the interfaces of energy storage devices such as Li-ion batteries and solid oxide electrocatalysis devices, we used ReaxFF and eReaxFF reactive molecular dynamics simulations in the following research areas: 1) In the electrode/electrolyte interface of a typical lithium-ion battery a solid electrolyte interphase layer is formed as a result of electrolyte decomposition during the initial charge/discharge cycles. Electron leakage from anode to the electrolyte reduces the Li+-ion and makes them more reactive resulting in decomposition of the organic electrolyte. To study the Li-electrolyte solvation, solvent exchange and subsequent solvent decomposition reactions at the anode/electrolyte interface, we have extended existing ReaxFF reactive force field parameter sets to organic electrolyte species such as ethylene carbonate, ethyl methyl carbonate, vinylene carbonate and LiPF6 salt. Density Functional Theory (DFT) data describing Li-associated initiation reactions for the organic electrolytes and binding energies of Li-electrolyte solvation structures were generated and added to existing ReaxFF training data and subsequently, we trained the ReaxFF parameters with the aim to find the optimal reproduction of the DFT data. In order to discern the characteristics of Li neutral and cation, we have introduced a second Li parameter set to describe Li+-ion. ReaxFF is trained for Li-neutral and Li+-cation to have similar solvation energies but unlike the neutral Li, Li+ will not induce reactivity in the organic electrolyte. Solvent decomposition reactions are presumed to happen once Li+-ions are reduced to Li-atoms, which can be simulated using a Monte-Carlo type atom modification within ReaxFF. This newly developed force field is capable of distinguishing between a Li-atom and a Li+-ion properly. Moreover, it is found that the solvent decomposition reaction barrier is a function of the number of EC molecules solvating the Li-atom. 2) Graphene, a 2D material arranged in an sp2-bonded hexagonal network, is one of the most promising materials for lithium-ion battery anodes due to its superior electronic conductivity, high surface area for lithium intercalation, fast ionic diffusivity and enhanced specific capacity. A detailed atomistic modeling of electronic conduction and non-zero voltage simulations of graphitic materials require the inclusion of an explicit electronic degree of freedom. To enable large length and time scale simulations of electron conduction in graphitic anodes, we developed an eReaxFF force field describing graphitic materials with an explicit electron concept. The newly developed force field, verified against quantum chemistry-based data describing, amongst others, electron affinities and equation of states, reasonably reproduces the behavior of electron conductivity in pristine and imperfect graphitic materials at different applied temperatures and voltages. Our eReaxFF description is capable of simulating leakage of excess electrons from graphene which are captured by exposed lithium ions; a common behavior at the anode/electrolyte interface of a lithium-ion battery. Finally, the initiation of Li-metal-plating observed at the graphene surface reveals the eReaxFF force field's potential for the future development of Li-graphene interactions with explicit electrons. 3) Electrocatalysis results in the change of the rate of an electrochemical reaction occurring on an electrode surface by varying the electrical potential. Electrocatalysis can be used in hydrogen generation and the generated hydrogen can be stored for future use in fuel cells for clean electricity. The use of solid oxide in electrocatalysis specially in hydrogen evolution reaction is promising. To enable large length and time scale atomistic simulations of solid oxide electrocatalysis for hydrogen generation, we developed an eReaxFF force field for barium zirconate doped with 20 mol% of yttrium (BZY20). All parameters for the eReaxFF were optimized to reproduce quantum mechanical (QM) calculations on relevant condensed phase and cluster systems describing oxygen vacancies, vacancy migrations, water adsorption, water splitting and hydrogen generation on the surfaces of the BZY20 solid oxide. Using the developed force field, we performed zero-voltage molecular dynamics simulations to observe water adsorption and the eventual hydrogen production. Based on our simulation results, we conclude that this force field sets a stage for the introduction of explicit electron concept in order to simulate electron conductivity and non-zero voltage effects on hydrogen generation. Overall, the work described in this dissertation demonstrate how atomistic-scale simulations can enhance our understanding of processes at interfaces in energy storage materials.
This handbook comprehensively covers the rapidly evolving field of power generation using triboelectric nanogenerators. Since their emergence in 2012, triboelectric nanogenerators have experienced fast development both in fundamental science aspects and technological innovations resulting in a plethora of outstanding applications and commercial opportunities in e.g. micro-nano energy systems, self-powered sensors, blue energy, and high-voltage power sources. The Handbook of Triboelectric Nanogenerators provides an indispensable overview of the state of the art in the field. It begins with a review of the physical and technological fundamentals and provides detailed coverage of triboelectric nanogenerators for cutting-edge applications from wearable electronics and medical implants to smart home sensing devices and human–machine interfacing. Edited and authored by active researchers in the field, the handbook offers a wealth of information for applied physicists and chemists, as well as materials scientists and engineers. In addition, mechanical and electronic engineers working in the fields of energy scavenging, power sources, and sensor-related application development will benefit greatly from the technical information presented in this groundbreaking reference work.
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
Multiscale simulations of atomistic/continuum coupling in computational materials science, where the scale expands from macro-/micro- to nanoscale, has become a hot research topic. These small units, usually nanostructures, are commonly anisotropic. The development of molecular modeling tools to describe and predict the mechanical properties of structures reveals an undeniable practical importance. Typical anisotropic structures (e.g. cubic, hexagonal, monoclinic) using DFT, MD, and atomic finite element methods are especially interesting, according to the modeling requirement of upscaling structures. It therefore connects nanoscale modeling and continuous patterns of deformation behavior by identifying relevant parameters from smaller to larger scales. These methodologies have the prospect of significant applications. I would like to recommend this book to both beginners and experienced researchers.
This book is based on a graduate course and suitable as a primer for any newcomer to the field, this book is a detailed introduction to the experimental and computational methods that are used to study how solid surfaces act as catalysts. Features include: First comprehensive description of modern theory of heterogeneous catalysis Basis for understanding and designing experiments in the field Allows reader to understand catalyst design principles Introduction to important elements of energy transformation technology Test driven at Stanford University over several semesters
Ab initio molecular dynamics revolutionized the field of realistic computer simulation of complex molecular systems and processes, including chemical reactions, by unifying molecular dynamics and electronic structure theory. This book provides the first coherent presentation of this rapidly growing field, covering a vast range of methods and their applications, from basic theory to advanced methods. This fascinating text for graduate students and researchers contains systematic derivations of various ab initio molecular dynamics techniques to enable readers to understand and assess the merits and drawbacks of commonly used methods. It also discusses the special features of the widely used Car–Parrinello approach, correcting various misconceptions currently found in research literature. The book contains pseudo-code and program layout for typical plane wave electronic structure codes, allowing newcomers to the field to understand commonly used program packages and enabling developers to improve and add new features in their code.
The school held at Villa Marigola, Lerici, Italy, in July 1997 was very much an educational experiment aimed not just at teaching a new generation of students the latest developments in computer simulation methods and theory, but also at bringing together researchers from the condensed matter computer simulation community, the biophysical chemistry community and the quantum dynamics community to confront the shared problem: the development of methods to treat the dynamics of quantum condensed phase systems.This volume collects the lectures delivered there. Due to the focus of the school, the contributions divide along natural lines into two broad groups: (1) the most sophisticated forms of the art of computer simulation, including biased phase space sampling schemes, methods which address the multiplicity of time scales in condensed phase problems, and static equilibrium methods for treating quantum systems; (2) the contributions on quantum dynamics, including methods for mixing quantum and classical dynamics in condensed phase simulations and methods capable of treating all degrees of freedom quantum-mechanically.
Exploring recent developments in the field, Coarse-Graining of Condensed Phase and Biomolecular Systems examines systematic ways of constructing coarse-grained representations for complex systems. It explains how this approach can be used in the simulation and modeling of condensed phase and biomolecular systems. Assembling some of the most influential, world-renowned researchers in the field, this book covers the latest developments in the coarse-grained molecular dynamics simulation and modeling of condensed phase and biomolecular systems. Each chapter focuses on specific examples of evolving coarse-graining methodologies and presents results for a variety of complex systems. The contributors discuss the minimalist, inversion, and multiscale approaches to coarse-graining, along with the emerging challenges of coarse-graining. They also connect atomic-level information with new coarse-grained representations of complex systems, such as lipid bilayers, proteins, peptides, and DNA.