Foreword xiii
About the Author xv
Preface xvii

Part I Frameworks 1

1 Introduction 3
1.1 Theoretical and Computational Chemistry 3
1.2 Multiscale Modeling 5
1.3 Orbital-based Theories 7
1.4 Density Functional Theory 13
1.5 Scope of This Book 18

2 Conceptual Density Functional Theory 23
2.1 Hypotheses and Brief History 23
2.2 Basic Formulation 25
2.3 Basic Concepts and Principles 33
2.4 Extensions 38
2.5 Concluding Remarks 46

3 Density-associated Quantities 53
3.1 Electron Density 54
3.2 Density Gradient and Laplacian 60
3.3 Topological Analysis 62
3.4 Quantum Theory of Atoms in Molecules 63
3.5 DAQ-based Indices 65
3.6 DAQs in Excited States 68
3.7 DAQ in Momentum Space 70
3.8 Concluding Remarks 71

4 Information-theoretic Approach 75
4.1 Overview 75
4.2 ITA Quantities 76
4.3 Four ITA Representations 80
4.4 Three ITA Principles 84
4.5 Two Identities Among ITA Quantities 87
4.6 Information Functional Theory 88
4.7 Applications for ITA Quantities 88
4.8 Conclusions and Outlook 89

5 Orbital-free Density Functional Theory 97
5.1 Overview 97
5.2 Theoretical Framework 100Contents vii
5.3 Descriptors from OF-DFT 110
5.4 Applications of OF-DFT 114
5.5 Concluding Remarks 114

6 Recent Advances in Density-based Frameworks 119
6.1 Relationship Among Four Frameworks 120
6.2 Topological Analysis of ITA Quantities 124
6.3 Energetic Information 126
6.4 ITA Extended to Pair Density 130
6.5 Extension to Excited States 132
6.6 Merging with Machine Learning 133
6.7 Concluding Remarks and Outlook 134

Part II Applications 139

7 Covalent and Noncovalent Interactions 141
7.1 Introduction 141
7.2 Orbital-based Approaches 143
7.3 Density-based Approaches 145
7.4 Energetics of Bonding 154
7.5 Recent Developments 156
7.6 Concluding Remarks 159

8 Cooperativity and Frustration 163
8.1 Introduction 163
8.2 Traditional Theory of Cooperativity 164
8.3 Quantification of Cooperativity in Density Functional Theory 166
8.4 Classical Theory of Frustration 172
8.5 Quantification of Frustration in DFT 174
8.6 Principle of Cooperativity and Frustrativity 178
8.7 Recent Advances 179
8.8 Outlook: From Cooperation and Frustration to Emergence 180

9 Homochirality and Principle of Chirality Hierarchy 183
9.1 What Is Chirality? 183
9.2 Homochirality and Theories of Homochirality 185
9.3 Types of Chirality and Chirality Hierarchy 186
9.4 Chirality Transmission 189
9.5 Chirality Hierarchy Case Study: Helices 189
9.6 Chirality Hierarchy Case Study: Propellers 192
9.7 Principle of Chirality Hierarchy 195
9.8 Concluding Remarks 196

10 Electrophilicity and Nucleophilicity 201
10.1 Introduction 201
10.2 Experimental Scales 203
10.3 Quantification in Conceptual Density Functional Theory 205
10.4 Quantification in ITA 211
10.5 Regioselectivity 214
10.6 Benchmark CDFT and ITA Quantifications 215
10.7 Ortho/Para and Meta Group Directing Effect 219
10.8 Concluding Remarks 221

11 Steric Effect and Stereoselectivity 225
11.1 Steric Effect 225
11.2 Stereoselectivity 228
11.3 Experimental Scales of Steric Effect 232
11.4 Steric Effect: A Density-based Quantification 234
11.5 Validation by Taft\'s Steric Parameters 238
11.6 Stereoselectivity: A Density-based Description 239
11.7 Quantification of Stereoselectivity 241
11.8 Summary and Conclusions 242

12 Acidity and Basicity 247
12.1 Introduction 247
12.2 Brønsted-Lowry Acidity and Basicity 249
12.3 CDFT and Brønsted-Lowry Acidity and Basicity 253