An Introduction to Coupled-Cluster Theory

T. Daniel Crawford

Contents

     1 Introduction

     2 Fundamental Concepts

          2.1 The Cluster Expansion

          2.2 The Cluster Operator

          2.3 Other Cluster-Based Wavefunctions

          2.4 Size-Extensivity and Size-Consistency

     3 Formal Coupled-Cluster Theory

          3.1 Construction of the General CC Equations

          3.2 Truncation of the CC Equations

          3.3 A Variational Coupled-Cluster Theory?

          3.4 The Hausdorff Expansion

     4 Practical Coupled-Cluster Theory

          4.1 Normal-Ordered Operators

          4.2 Wick's Theorem

          4.3 The Normal-Ordered Hamiltonian

          4.4 Algebraic Construction of the CCD Equations

          4.5 Diagrammatic Construction of the CCD Equations

     A Second Quantization

          A.1 Creation and Annihilation Operators

          A.2 Second-Quantized Representation of Operators

          A.3 Usefulness of Second-Quantized Operators

     B Relationship to Configuration Interaction

     References

     Index 

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