Written by two leading experts in the field, this book explores the 'many-body' methods that have become the dominant approach in determining molecular structure, properties and interactions. With a tight focus on the highly popular Many-Body Perturbation Theory (MBPT) and Coupled-Cluster theories (CC), the authors present a simple, clear, unified approach to describe the mathematical tools and diagrammatic techniques employed. Using this book the reader will be able to understand, derive and confidently implement relevant algebraic equations for current and even new multi-reference CC methods. Hundreds of diagrams throughout the book enhance reader understanding through visualization of computational procedures and extensive referencing allows further exploration of this evolving area. With an extensive bibliography and detailed index, this book will be suitable for graduates and researchers within quantum chemistry, chemical physics and atomic, molecular and solid-state physics.

Advances in Quantum Chemistry, Volume 86 highlights new advances in the field, with this new volume presenting topics covering Can orbital basis sets compete with explicitly correlated ones for few-electron systems?, Converging high-level equation-of-motion coupled-cluster energetics with the help of Monte Carlo and selected configuration interaction, Coupled cluster downfolding techniques: a review of existing applications in classical and quantum computing for chemical systems, Multi-reference methods for the description of dynamic and nondynamic electron correlation effects in atoms and molecules, Exploring the attosecond laser-driven electron dynamics in the hydrogen molecule with different TD-CI approaches, and much more. Additional sections cover Molecular systems in spatial confinement: variation of linear and nonlinear electrical response of molecules in the bond dissociation processes, Relativistic Infinite-order two-component methods for heavy elements, Second quantized approach to exchange energy revised - beyond the S^2 approximation, Calculating atomic states without the Born-Oppenheimer approximation, Convergence of the Correlated Optimized Effective Potential Method, and more.