Exploration on Quantum Chemical Potential Energy Surfaces


Book Description

Providing several examples, this book describes fundamental methods and techniques specific for efficient exploration on the potential energy surface by quantum chemical calculations.




Ab Initio Molecular Dynamics Analysis Based on Reduced-Dimensionality Reaction Route Map


Book Description

This thesis proposes useful tools, on-the-fly trajectory mapping method and Reaction Space Projector (ReSPer), to analyze chemical reaction mechanisms by combining the reaction route map and the ab initio molecular dynamics. The key concept for the proposed tools is the Cartesian distance between pairwise molecular structures, and a practical procedure to get the optimal distance is introduced. The on-the-fly trajectory mapping method tracks the distance function between reference structures and molecular structures along the trajectory. Although this method provides fruitful insight into dynamic reaction behaviors, the visualization of reaction routes into a low-dimensional space is still challenging because of the multi-dimensionality. ReSPer successfully constructs a low-dimensional reaction space defined by mathematically-selected principal coordinates representing mutual distance relationships in the full-dimensional space. ReSPer also enables us to project trajectories into the reaction space in the reduced dimension. In this thesis, these methods are applied to several reactions, including bifurcating and photochemical reactions, revealing dynamically-allowed reaction mechanisms. This thesis provides robust and versatile tools to elucidate dynamical reaction routes on the basis of the reduced-dimensionality reaction route map and will help control chemical reaction dynamics and select descriptors for machine learning.




New Horizons in Computational Chemistry Software


Book Description

This volume presents the current status of software development in the field of computational and theoretical chemistry and gives an overview of the emerging trends. The challenges of maintaining the legacy codes and their adaptation to the rapidly growing hardware capabilities and the new programming environments are surveyed in a series of topical reviews written by the core developers and maintainers of the popular quantum chemistry and molecular dynamics programs. Special emphasis is given to new computational methodologies and practical aspects of their implementation and application in the computational chemistry codes. Modularity of the computational chemistry software is an emerging concept that enables to bypass the development and maintenance bottleneck of the legacy software and to customize the software using the best available computational procedures implemented in the form of self-contained modules. Perspectives on modular design of the computer programs for modeling molecular electronic structure, non-adiabatic dynamics, kinetics, as well as for data visualization are presented by the researchers actively working in the field of software development and application. This volume is of interest to quantum and computational chemists as well as experimental chemists actively using and developing computational software for their research. Chapters "MLatom 2: An Integrative Platform for Atomistic Machine Learning” and “Evolution of the Automatic Rhodopsin Modeling (ARM) Protocol" are available open access under a CC BY 4.0 License via link.springer.com.




Exploring Chemical Concepts Through Theory and Computation


Book Description

Deep, theoretical resource on the essence of chemistry, explaining the sixteen most important concepts including redox states and bond types Exploring Chemical Concepts Through Theory and Computation provides a comprehensive account of how the three widely used theoretical frameworks of valence bond theory, molecular orbital theory, and density functional theory, along with a variety of important chemical concepts, can between them describe and efficiently and reliably predict key chemical parameters and phenomena. By comparing the three main theoretical frameworks, readers will become competent in choosing the right modeling approach for their task. The authors go beyond a simple comparison of existing algorithms to show how data-driven theories can explain why chemical compounds behave the way they do, thus promoting a deeper understanding of the essence of chemistry. The text is contributed to by top theoretical and computational chemists who have turned computational chemistry into today's data-driven and application-oriented science. Exploring Chemical Concepts Through Theory and Computation discusses topics including: Orbital-based approaches, density-based approaches, chemical bonding, partial charges, atoms in molecules, oxidation states, aromaticity and antiaromaticity, and acidity and basicity Electronegativity, hardness, softness, HSAB, sigma-hole interactions, charge transport and energy transfer, and homogeneous and heterogeneous catalysis Electrophilicity, nucleophilicity, cooperativity, frustration, homochirality, and energy decomposition Chemical concepts in solids, excited states, spectroscopy and machine learning, and catalysis and machine learning, and as well as key connections between related concepts Aimed at both novice and experienced computational, theoretical, and physical chemists, Exploring Chemical Concepts Through Theory and Computation is an essential reference to gain a deeper, more advanced holistic understanding of the field of chemistry as a whole.




Advances in Bioinformatics and Computational Biology


Book Description

This book constitutes the refereed proceedings of the Brazilian Symposium on Bioinformatics, BSB 2020, held in São Paulo, Brazil, in November 2020. Due to COVID-19 pandemic the conference was held virtually The 20 revised full papers and 5 short papers were carefully reviewed and selected from 45 submissions. The papers address a broad range of current topics in computational biology and bioinformatics.







Chemistry at the Frontier with Physics and Computer Science


Book Description

Chemistry at the Frontier with Physics and Computer Science: Theory and Computation shows how chemical concepts relate to their physical counterparts and can be effectively explored via computational tools. It provides a holistic overview of the intersection of these fields and offers practical examples on how to solve a chemical problem from a theoretical and computational perspective, going from theory to models, methods and implementation. Sections cover both sides of the Born-Oppenheimer approximation (nuclear dynamics and electronic structure), chemical reactions, chemical bonding, and cover theory to practice on three related physical problems (wavepacket dynamics, Hartree-Fock equations and electron-cloud redistribution). Drawing on the interdisciplinary knowledge of its expert author, this book provides a contemporary guide to theoretical and computational chemistry for all those working in chemical physics, physical chemistry and related fields. - Combines a 'big picture' overview of chemistry as it relates to physics and computer science, including detailed guidance on tackling chemistry problems from both theoretical and computational perspectives - Treats nuclear dynamics and electronic structure on the same footing in discussions of the Born-Oppenheimer approximation - Includes examples of scientific programming in modern Fortran for problems related to the modeling of chemical reaction dynamics and the analysis of chemical bonding




Properties of Chemically Interesting Potential Energy Surfaces


Book Description

Contemporary chemical reaction theory is the characterization of Potential Energy Hypersurfaces (PES). The authors critically analyze chemically and mathematically suitable reaction path definitions. The book presents a simple mathematical analysis of stationary and critical points of the PES. It provides tools for studying chemical reactions by calculating reaction paths and related curves. A further aspect of the book is the dependence of PES properties on approximations used for the analysis. Recent quantum chemical calculations, particularly of single proton transfer processes, and experimental data are compared. The book addresses students and researchers in Theoretical Chemistry, Chemical Kinetics and related fields.




Computational Approaches for Chemistry Under Extreme Conditions


Book Description

This book presents recently developed computational approaches for the study of reactive materials under extreme physical and thermodynamic conditions. It delves into cutting edge developments in simulation methods for reactive materials, including quantum calculations spanning nanometer length scales and picosecond timescales, to reactive force fields, coarse-grained approaches, and machine learning methods spanning microns and nanoseconds and beyond. These methods are discussed in the context of a broad range of fields, including prebiotic chemistry in impacting comets, studies of planetary interiors, high pressure synthesis of new compounds, and detonations of energetic materials. The book presents a pedagogical approach for these state-of-the-art approaches, compiled into a single source for the first time. Ultimately, the volume aims to make valuable research tools accessible to experimentalists and theoreticians alike for any number of scientific efforts, spanning many different types of compounds and reactive conditions.




Exploring the Universe: From Near Space to Extra-Galactic


Book Description

This Festschrift dedicated to the 60th birth anniversary of Prof. Sandip K. Chakrabarti, a well-known Indian astrophysicist, presents a collection of contributions by about fifty scientists who work on diverse topics in contemporary astrophysics and space science including new and low-cost balloon borne experiments, planetary science, astrochemistry and the origin of life, ionospheric research and earthquake predictions, relativistic astrophysics around black holes, and finally, the observational signatures and radiative properties of compact objects. All the authors are well known scholars in their respective subject and are all PhD students of Prof. Sandip K. Chakrabarti. The book demonstrates a two-dimensional evolution of research areas triggered by Sandip Chakrabarti over the past few decades. The first dimension represents the evolution and diversification of Chakrabarti’s own research in which new students were trained. A second dimension arises from the evolution of the research topics pursued by Chakrabarti’s fifty odd doctoral students, many of whom have become renowned scientists in their own right, after starting with a certain subject under Chakrabarti and then migrating to completely new subjects with dexterity. The editors have compiled and edited the articles appropriately to some extent to suit the spirit of this Festschrift on the one hand and to keep balance in diverse topics on the other. Thus this volume also provides an overview for whosoever wishes to enter the important subjects of compact objects, astrochemistry, ionospheric science or space exploration in near space. New graduates, PhD scholars, teachers and researchers will benefit from this volume. Moreover it is a record of tremendous success of a school in a range of vast topics.