Quantum mechanics is the fundamental theory of matter on the microscopic scale. Thanks to conceptual advances and progress in computer technology, its application to the study of atomic and molecular systems, which is of relevance to chemistry, physics, biology, and materials science, is a rapidly developing research area. Advances in the Theory of Atomic and Molecular Systems is a two-volume collection of 33 papers that define its leading edge: they present recent theoretical and computational developments that provide new insights into the structure, properties, and behavior of a variety of atomic and molecular systems. These papers are a selection of some of the most out-standing presentations made at the 13th International Workshop on Quantum Systems in Chemistry and Physics (QSCP-XIII), held at Lansing, Michigan, USA, in July 2008. Since the QSCP-XIII workshop was coordinated with the 6th Congress of the International Society for Theoretical Chemical Physics (ISTCP-VI) held at Vancouver, British Columbia, Canada, in July 2008 as well, three of the 33 papers included in the present two volumes have been written by ISTCP-VI participants.

"Advances in the Theory of Atomic and Molecular Systems, is a collection of contributions presenting recent theoretical and computational developments that provide new insights into the structure, properties, and behavior of a variety of atomic and molecular systems. This volume (subtitled: Conceptual and Computational Advances in Quantum Chemistry) focuses on electronic structure theory and its foundations.This volume is an invaluable resource for faculty, graduate students, and researchers interested in theoretical and computational chemistry and physics, physical chemistry and chemical physics, molecular spectroscopy, and related areas of science and engineering."

Historical Overviews.- An Illustrated Overview of the Origins and Development of the QSCP Meetings.- Methylene: A Personal Perspective.- High-Precision Quantum Chemistry.- Free Complement Method for Solving the Schrödinger Equation: How Accurately Can We Solve the Schrödinger Equation.- Energy Computation for Exponentially Correlated Four-Body Wavefunctions.- Beyond Nonrelativistic Theory: Relativity and QED.- The Equivalence Principle from a Quantum Mechanical Perspective.- Relativistically Covariant Many-Body Perturbation Procedure.- Relativistic Variational Calculations for Complex Atoms.- Advances in Wave Function Methods.- Linear Scaling Local Correlation Extensions of the Standard and Renormalized Coupled-Cluster Methods.- The Correlation Consistent Composite Approach (ccCA): Efficient and Pan-Periodic Kinetics and Thermodynamics.- On the Performance of a Size-Extensive Variant of Equation-of-Motion Coupled Cluster Theory for Optical Rotation in Chiral Molecules.- Performance of Block Correlated Coupled Cluster Method with the CASSCF Reference Function for Carbon-Carbon Bond Breaking in Hydrocarbons.- Fermi-Vacuum Invariance in Multiconfiguration Perturbation Theory.- On the Wave Function of Coulson and Fischer: A Third Way in Quantum Chemistry.- Advances in Density Functional Theory.- Energy Densities of Exchange and Correlation in the Slowly Varying Region of the Airy Gas.- Orbital-Free Embedding Effective Potential in Analytically Solvable Cases.- A Simple Analytical Density Model for Atoms and Ions Based on a Semiexplicit Density Functional.- Advances in Concepts and Models.- The Jahn-Teller Effect: Implications in Electronic Structure Calculations.- Rules for Excited States of Degenerate Systems: Interpretation by Frozen Orbital Analysis.- TheDissociation Catastrophe in Fluctuating-Charge Models and its Implications for the Concept of Atomic Electronegativity.- Information Planes and Complexity Measures for Atomic Systems, Ionization Processes and Isoelectronic Series.