<p>List of Contributors xvii</p> <p>Preface xxv<br /><b><br />1 Levy–Perdew–Sahni Equation and the Kohn–Sham Inversion Problem 1<br /> </b><i>Ashish Kumar and Manoj K. Harbola</i></p> <p>1.1 Introduction 1</p> <p>1.2 One Equation ⟹ Several Methods; Universal Nature of Different Density-Based Kohn–Sham Inversion Algorithms 2</p> <p>1.2.1 Generating Functional S[ρ] of Density-Based Kohn–Sham Inversion 2</p> <p>1.2.2 Condition on Generating Functional S[ρ] 4</p> <p>1.2.3 Examples of Different Generating Functionals 5</p> <p>1.2.4 Application to Spherical Systems 7</p> <p>1.2.5 Using Random Numbers to do Density-to-Potential Inversion 10</p> <p>1.3 General Penalty Method for Density-to-Potential Inversion 12</p> <p>1.4 Understanding Connection Between Density and Wavefunction-Based Inversion Methods Using LPS Equation 16</p> <p>1.5 Concluding Remarks 19</p> <p>Acknowledgments 19</p> <p>References 20</p> <p><b>2 Electron Density, Density Functional Theory, and Chemical Concepts 27<br /> </b><i>Swapan K. Ghosh</i></p> <p>2.1 Introduction 27</p> <p>2.2 Viewing Chemical Concepts Through a DFT Window 27</p> <p>2.3 Electron Fluid, Quantum Fluid Dynamics, Electronic Entropy, and a Local Thermodynamic Picture 30</p> <p>2.4 Miscellaneous Offshoots from Electron Density Experience 31</p> <p>2.5 Concluding Remarks 31</p> <p>Acknowledgments 32</p> <p>References 32</p> <p><b>3 Local and Nonlocal Descriptors of the Site and Bond Chemical Reactivity of Molecules 35<br /> </b><i>José L. Gázquez, Paulino Zerón, Maurizio A. Pantoja-Hernández and Marco Franco-Pérez</i></p> <p>3.1 Introduction 35</p> <p>3.2 Local and Nonlocal Reactivity Indexes 38</p> <p>3.3 Site and Bond Reactivities 42</p> <p>3.4 Concluding Remarks 46</p> <p>Acknowledgment 47</p> <p>References 47</p> <p><b>4 Relativistic Treatment of Many-Electron Systems Through DFT in CCG 53<br /> </b><i>Shamik Chanda and Amlan K. Roy</i></p> <p>4.1 Introduction 53</p> <p>4.2 Theoretical Framework 56</p> <p>4.2.1 Dirac Equation 56</p> <p>4.2.2 Relativistic Density Functional Theory: Dirac–Kohn–Sham Method 58</p> <p>4.2.3 Decoupling of Dirac Hamiltonian: DKH Methodology 60</p> <p>4.2.4 DFT in Cartesian Grid 62</p> <p>4.2.4.1 Basic Methodology 62</p> <p>4.2.4.2 Hartree Potential in CCG 63</p> <p>4.2.4.3 Hartree Fock Exchange Through FCT in CCG 65</p> <p>4.2.4.4 Orbital-Dependent Hybrid Functionals via RS-FCT 65</p> <p>4.3 Computational Details 66</p> <p>4.4 Results and Discussion 67</p> <p>4.4.1 One-Electron Atoms 67</p> <p>4.4.2 Many-Electron Systems 68</p> <p>4.4.2.1 Grid Optimization 68</p> <p>4.4.2.2 Ground-State Energy of Atoms and Molecules 70</p> <p>4.4.3 Application to Highly Charged Ions: He- and Li-Isoelectronic Series 71</p> <p>4.5 Future and Outlook 74</p> <p>Acknowledgement 76</p> <p>References 76</p> <p><b>5 Relativistic Reduced Density Matrices: Properties and Applications 83<br /> </b><i>Somesh Chamoli, Malaya K. Nayak and Achintya Kumar Dutta</i></p> <p>5.1 Introduction 83</p> <p>5.2 Relativistic One-Body Reduced Density Matrix 84</p> <p>5.3 Properties of Relativistic 1-RDM 85</p> <p>5.3.1 Natural Spinors: An Efficient Framework for Low-cost Calculations 87</p> <p>5.3.1.1 Correlation Energy 88</p> <p>5.3.1.2 Bond Length and Harmonic Vibrational Frequency 90</p> <p>5.3.2 Natural Spinors as an Interpretive Tool 93</p> <p>5.4 Concluding Remarks 93</p> <p>Acknowledgments 93</p> <p>References 94</p> <p><b>6 Many-Body Multi-Configurational Calculation Using Coulomb Green’s Function 97<br /> </b><i>Bharti Kapil, Shivalika Sharma, Priyanka Aggarwal, Harsimran Kaur, Sunny Singh and Ram Kuntal Hazra</i></p> <p>6.1 Introduction 97</p> <p>6.2 Theoretical Development 98</p> <p>6.2.1 Presence of Magnetic Field 99</p> <p>6.2.1.1 3D Electron Gas Model 99</p> <p>6.2.1.2 2D Electron Gas Model 103</p> <p>6.2.1.3 3D Exciton Model 107</p> <p>6.2.1.4 2D Exciton Model 109</p> <p>6.2.2 Absence of Magnetic Field 114</p> <p>6.2.2.1 3D He-Isoelectronic Ions 114</p> <p>6.2.2.2 2D He-Isoelectronic Ions 119</p> <p>6.2.2.3 Energy Calculation Through Perturbation 122</p> <p>6.2.2.4 Current Density of 2-e System 123</p> <p>6.3 Results and Discussion 123</p> <p>6.3.1 3D Interacting Electron Gas 123</p> <p>6.3.2 2D Interacting Electron Gas 125</p> <p>6.3.3 3D Exciton Complexes 126</p> <p>6.3.4 2D Exciton Complexes 127</p> <p>6.3.5 3D He-Isoelectronic Species 128</p> <p>6.3.5.1 Analysis of E<sup>(2)</sup><sub>0</sub> of He-Isoelectronic Ions 129</p> <p>6.3.5.2 Analysis of E<sup>(3)</sup><sub>0</sub> of He-Isoelectronic Ions 129</p> <p>6.3.6 2D He-Isoelectronic Species 130</p> <p>6.4 Concluding Remarks 131</p> <p>Acknowledgments 131</p> <p>6.A Standard Equations and Integrals 132</p> <p>References 133</p> <p><b>7 Excited State Electronic Structure – Effect of Environment 137<br /> </b><i>Supriyo Santra and Debashree Ghosh</i></p> <p>7.1 Introduction 137</p> <p>7.2 Methodology 138</p> <p>7.2.1 Quantum Mechanical Methods 138</p> <p>7.2.1.1 Time-Dependent Density Functional Theory 138</p> <p>7.2.1.2 Active Space-Based Methods 138</p> <p>7.2.1.3 Configuration Interaction-Based Approaches 139</p> <p>7.2.1.4 Equation of Motion Coupled Cluster 140</p> <p>7.2.2 Molecular Mechanical Methods 140</p> <p>7.2.2.1 Oniom 141</p> <p>7.2.2.2 Mechanical Embedding 141</p> <p>7.2.2.3 Electronic Embedding 142</p> <p>7.2.2.4 Polarizable Embedding 142</p> <p>7.3 Representative Examples 143</p> <p>7.3.1 Photo-Isomerization of Rhodopsin 143</p> <p>7.3.2 DNA-Base Excited States in Solution 143</p> <p>7.3.3 Green Fluorescent Proteins 145</p> <p>7.4 Conclusion 146</p> <p>Acknowledgement 146</p> <p>References 146</p> <p><b>8 Electron Density in the Multiscale Treatment of Biomolecules 149<br /></b><i>Soumyajit Karmakar, Sunita Muduli, Atanuka Paul, and Sabyashachi Mishra</i></p> <p>8.1 Introduction 149</p> <p>8.2 Theoretical Background 150</p> <p>8.2.1 Hybrid Quantum Mechanics–Molecular Mechanics Approach 152</p> <p>8.3 Polarizable Density Embedding 155</p> <p>8.4 Multi-Scale QM/MM with Extremely Localized Molecular Orbitals 157</p> <p>8.5 Multiple Active Zones in QM/MM Modelling 159</p> <p>8.6 Reactivity Descriptors with QM/MM Modeling 161</p> <p>8.7 Treatment of Hydrogen Bonding with QM/MM 163</p> <p>8.8 Quantum Refinement of Crystal Structure with QM/MM 164</p> <p>8.9 Concluding Remarks 166</p> <p>Acknowledgments 167</p> <p>References 167</p> <p><b>9 Subsystem Communications and Electron Correlation 173<br /> </b><i>Roman F. Nalewajski</i></p> <p>9.1 Introduction 173</p> <p>9.2 Discrete and Local Probability Networks in Molecular Bond Systems 174</p> <p>9.3 Bond Descriptors of Molecular Communication Channels 177</p> <p>9.4 Hartree–Fock Communications and Fermi Correlation 179</p> <p>9.5 Communication Partitioning of Two-Electron Probabilities 181</p> <p>9.6 Communications in Interacting Subsystems 184</p> <p>9.7 Illustrative Application to Reaction HSAB Principle 188</p> <p>9.8 Conclusion 191</p> <p>References 192</p> <p><b>10 Impacts of External Electric Fields on Aromaticity and Acidity for Benzoic Acid and Derivatives: Directionality, Additivity, and More 199<br /> </b><i>Meng Li, Xinjie Wan, Xin He, Chunying Rong, Dongbo Zhao, and Shubin Liu</i></p> <p>10.1 Introduction 199</p> <p>10.2 Methodology 199</p> <p>10.3 Computational Details 202</p> <p>10.4 Results and Discussion 203</p> <p>10.5 Conclusions 213</p> <p>Acknowledgments 213</p> <p>References 213</p> <p><b>11 A Divergence and Rotational Component in Chemical Potential During Reactions 217<br /> </b><i>Jean-Louis Vigneresse</i></p> <p>11.1 Introduction 217</p> <p>11.2 Chemical Descriptors 218</p> <p>11.3 Charge and Energy Exchange 219</p> <p>11.4 Fitness Landscape Diagrams 219</p> <p>11.5 Chemical Reactions 220</p> <p>11.6 Examining the Charge Exchange 221</p> <p>11.6.1 Path p<sub>χη</sub>(ζ) and Charge Exchange 221</p> <p>11.6.2 Systematic Changes Depending on the Starting Points on p<sub>χη</sub>(ζ) 223</p> <p>11.6.3 Specific Solutions Using a p<sub>ηω</sub> Path 224</p> <p>11.7 Significance and Applications 225</p> <p>11.8 Conclusions 227</p> <p>Acknowledgments 227</p> <p>References 228</p> <p><b>12 Deep Learning of Electron Density for Predicting Energies: The Case of Boron Clusters 231<br /> </b><i>Pinaki Saha and Minh Tho Nguyen</i></p> <p>12.1 Introduction 231</p> <p>12.2 Deep Learning of Electron Density 233</p> <p>12.3 Neural Networks for Neutral Boron Clusters 235</p> <p>12.4 Concluding Remarks 242</p> <p>Acknowledgements 243</p> <p>References 243</p> <p><b>13 Density-Based Description of Molecular Polarizability for Complex Systems 247<br /> </b><i>Dongbo Zhao, Xin He, Paul W. Ayers and Shubin Liu</i></p> <p>13.1 Introduction 247</p> <p>13.2 Methodology and Computations 248</p> <p>13.2.1 Information-Theoretic Approach (ITA) Quantities 248</p> <p>13.2.2 The GEBF Method 249</p> <p>13.3 Results and Discussion 250</p> <p>13.4 Conclusions and Perspectives 260</p> <p>Acknowledgment 261</p> <p>References 261</p> <p><b>14 Conceptual Density Functional Theory-Based Study of Pure and TMs-Doped cdx (X = S, Se, Te; TMs = Cu, Ag, and Au) Nano Cluster for Water Splitting and Spintronic Applications 265<br /> </b><i>Prabhat Ranjan, Preeti Nanda, Ramon Carbó-Dorca, and Tanmoy Chakraborty</i></p> <p>14.1 Introduction 265</p> <p>14.2 Methodology 266</p> <p>14.3 Results and Discussion 267</p> <p>14.3.1 Electronic Properties and CDFT-Based Descriptors 267</p> <p>14.4 Conclusion 275</p> <p>Acknowledgments 275</p> <p>Funding 276</p> <p>References 276</p> <p><b>15 “Phylogenetic” Screening of External Potential Related Response Functions 279<br /></b><i>Paweł Szarek</i></p> <p>15.1 Introduction 279</p> <p>15.2 Alchemical Approach 281</p> <p>15.3 The “Family Tree” 281</p> <p>15.4 First-order Sensitivities 282</p> <p>15.5 Second-Order Sensitivities 283</p> <p>15.5.1 Electric Dipole Polarizability 283</p> <p>15.5.2 “Polarizability Potential” – Local Polarization 284</p> <p>15.6 Alchemical Hardness 285</p> <p>15.6.1 Local Alchemical Hardness 287</p> <p>15.7 Alchemical Characteristic Radius 289</p> <p>15.8 Linear Response Function 291</p> <p>15.9 Conclusions 292</p> <p>References 293</p> <p><b>16 On the Nature of Catastrophe Unfoldings Along the Diels–Alder Cycloaddition Pathway 299<br /> </b><i>Leandro Ayarde-Henríquez, Cristian Guerra, Mario Duque-Noreña, Patricia Pérez, Elizabeth Rincón and Eduardo Chamorro</i></p> <p>16.1 Introduction 299</p> <p>16.2 Molecular Symmetry and Elementary Catastrophe Unfoldings 301</p> <p>16.2.1 The Case of Normal- and Inverse-Electron-Demand Diels–Alder Reactions 301</p> <p>16.2.2 The C—C Bond Breaking in a High Symmetry Environment 304</p> <p>16.2.3 The Photochemical Ring Opening of 1,3-Cyclohexadiene 305</p> <p>16.3 Concluding Remarks 306</p> <p>Acknowledgments 307</p> <p>References 307</p> <p><b>17 Designing Principles for Ultrashort H···H Nonbonded Contacts and Ultralong C—C Bonds 313<br /> </b><i>Nilangshu Mandal and Ayan Datta</i></p> <p>17.1 Introduction 313</p> <p>17.1.1 The Art of the Chemical Bond 314</p> <p>17.1.2 Designing and Decoding Chemical Bond 314</p> <p>17.2 Governing Factors for Ultrashort H···H Nonbonded Contacts 315</p> <p>17.2.1 London Dispersion Interaction 316</p> <p>17.2.2 Polarity and Charge Separation 317</p> <p>17.2.3 Conformations and Orientations 317</p> <p>17.2.4 Iron Maiden Effect 318</p> <p>17.3 Elongation Strategies for C—C Bonds 319</p> <p>17.3.1 Steric Crowding Effect 320</p> <p>17.3.2 Core–Shell Strategy and Scissor Effect 321</p> <p>17.3.3 Negative Hyperconjugation Effect 321</p> <p>17.4 Concluding Remarks 323</p> <p>Acknowledgments 324</p> <p>References 324</p> <p><b>18 Accurate Determination of Materials Properties: Role of Electron Density 329<br /></b><i>Anup Pramanik, Sourav Ghoshal, Santu Biswas, Biplab Rajbanshi and Pranab Sarkar</i></p> <p>18.1 Introduction 329</p> <p>18.2 Materials Properties: Structure and Electronic Properties 330</p> <p>18.2.1 Classification of Materials 330</p> <p>18.2.2 Electronic Properties of Materials 332</p> <p>18.3 Molecules to Materials, Essential Role of Electron Density 333</p> <p>18.3.1 The Density Functional Theory (DFT) 334</p> <p>18.3.2 The Hohenberg–Kohn Theorems 334</p> <p>18.3.3 The Hohenberg–Kohn Variational Theorems 335</p> <p>18.3.4 The Kohn–Sham (KS) Method 335</p> <p>18.3.5 Local Density Approximation 337</p> <p>18.3.6 Generalized Gradient Approximation 337</p> <p>18.3.7 Meta-GGA and Hybrid Functionals 338</p> <p>18.4 Further Approximations in DFT 339</p> <p>18.4.1 The Density Functional Tight-Binding Theory 339</p> <p>18.4.2 Self-Consistent-Charge Density-Functional Tight-Binding (SCC-DFTB) Method 340</p> <p>18.5 Solar Cell Materials, Interfacial Charge Transfer Phenomena 340</p> <p>18.5.1 The Time-Dependent Density Functional Theory 342</p> <p>18.5.2 TDDFT and Linear Response 343</p> <p>18.5.3 Excitation Energy and Excited State Properties 344</p> <p>18.5.3.1 Exciton Binding Energy 346</p> <p>18.5.3.2 Reorganization Energy 346</p> <p>18.5.3.3 The Rates of Charge Transfer and Recombination Processes 347</p> <p>18.6 Concluding Remarks 348</p> <p>Acknowledgements 349</p> <p>References 349</p> <p><b>19 A Conceptual DFT Analysis of Mechanochemical Processes 355<br /> </b><i>Ruchi Jha, Shanti Gopal Patra, Debdutta Chakraborty, and Pratim Kumar Chattaraj</i></p> <p>19.1 Introduction 355</p> <p>19.2 Theoretical Background 356</p> <p>19.2.1 The Constrained Geometries Simulate External Force (COGEF) 356</p> <p>19.2.2 External Force is Explicitly Included (EFEI) 358</p> <p>19.3 Results and Discussions 358</p> <p>19.3.1 General Consideration 358</p> <p>19.3.2 Constrained Geometries Simulate External Force (COGEF) 360</p> <p>19.3.2.1 Mechanochemical CDFT Reactivity Descriptors and Their Application to Diatomic Molecules 362</p> <p>19.3.3 Understanding Ball Milling Mechanochemical Processes with DFT Calculations and Microkinetic Modeling 365</p> <p>19.3.4 Explicit Force 369</p> <p>19.3.5 Dynamical Aspect of Mechanochemistry 369</p> <p>19.4 Concluding Remarks 373</p> <p>Acknowledgments 373</p> <p>References 373</p> <p><b>20 Molecular Electron Density and Electrostatic Potential and Their Applications 379<br /> </b><i>Shyam V.K. Panneer, Masiyappan Karuppusamy, Kanagasabai Balamurugan, Sathish K. Mudedla, Mahesh K. Ravva and Venkatesan Subramanian</i></p> <p>20.1 Introduction 379</p> <p>20.2 Topography Analysis of Scalar Fields 380</p> <p>20.2.1 Molecular Electron Density 380</p> <p>20.2.2 Topology of Molecular Electrostatic Potential 381</p> <p>20.3 Usefulness of MESP and MED Analysis for Understanding Weak Interactions 382</p> <p>20.3.1 MESP and MED Topography Analysis of Oligomers of Conjugated Polymers and their Interaction with PCBM Acceptors 382</p> <p>20.3.2 Interaction of Small Molecules with Models of Single-Walled Carbon Nanotube and Graphene 386</p> <p>20.3.2.1 Interaction of Nucleobases with Carbon Nanomaterials 386</p> <p>20.3.2.2 Interaction of Chlorobenzene with Carbon Nanomaterials 392</p> <p>20.3.2.3 Interaction of Carbohydrates with Carbon Nanomaterials 394</p> <p>20.4 Conclusion 397</p> <p>Acknowledgment 398</p> <p>Conflict of Interest 398</p> <p>References 398</p> <p><b>21 Origin and Nature of Pancake Bonding Interactions: A Density Functional Theory and Information-Theoretic Approach Study 401<br /> </b><i>Dongbo Zhao, Xin He and Shubin Liu</i></p> <p>21.1 Introduction 401</p> <p>21.2 Methodology 402</p> <p>21.2.1 Interaction Energy and Its Components in DFT 402</p> <p>21.2.2 Information-Theoretic Approach Quantities 403</p> <p>21.3 Computational Details 404</p> <p>21.4 Results and Discussion 404</p> <p>21.5 Concluding Remarks 410</p> <p>Acknowledgment 411</p> <p>References 411</p> <p><b>22 Electron Spin Density and Magnetism in Organic Diradicals 415<br /> </b><i>Suranjan Shil, Debojit Bhattacharya and Anirban Misra</i></p> <p>22.1 Introduction 415</p> <p>22.2 Quantitative Relation Between Magnetic Exchange Coupling Constant and Spin Density 416</p> <p>22.3 Spin Density Alternation 416</p> <p>22.3.1 Phenyl Nitroxide 416</p> <p>22.3.2 Methoxy Phenyl Nitroxide 417</p> <p>22.3.3 Phenyl Nitroxide Coupled Through Methylene 417</p> <p>22.3.4 Spin Density of Radical Systems 418</p> <p>22.3.5 Distance Dependence of Spin Density 418</p> <p>22.3.6 Geometry Dependence of Spin Density 423</p> <p>22.3.7 Dependence on Connecting Atoms 423</p> <p>22.4 Concluding Remarks 427</p> <p>Acknowledgements 427</p> <p>References 428</p> <p><b>23 Stabilization of Boron and Carbon Clusters with Transition Metal Coordination – An Electron Density and DFT Study 431<br /> </b><i>Amol B. Rahane, Rudra Agarwal, Pinaki Saha, Nagamani Sukumar and Vijay Kumar</i></p> <p>23.1 Introduction 431</p> <p>23.2 Computational Details 434</p> <p>23.3 Results and Discussion 435</p> <p>23.3.1 Structures and Stability of Metal Atom Encapsulated Boron Clusters 435</p> <p>23.3.2 Bonding Characteristics in M@B<sub>18</sub>, M@B<sub>20</sub>, M@B<sub>22</sub>, and M@B<sub>24</sub> Clusters 440</p> <p>23.3.3 Structures and Stability of Carbon Rings 447</p> <p>23.3.4 Bonding Characteristics in Carbon Rings 450</p> <p>23.4 Conclusions 457</p> <p>Acknowledgments 458</p> <p>References 458</p> <p><b>24 DFT-Based Computational Approach for Structure and Design of Materials: The Unfinished Story 465<br /> </b><i>Ravi Kumar, Mayank Khera, Shivangi Garg, and Neetu Goel</i></p> <p>24.1 Introduction 465</p> <p>24.2 Different Frameworks of DFT 466</p> <p>24.2.1 Kohn Sham Density Functional Theory (KS-DFT) 466</p> <p>24.2.2 Time-Dependent Density Functional Theory (TD-DFT) 467</p> <p>24.2.3 Linear Response Time-Dependent Density-Functional Theory (LR-TDDFT) 469</p> <p>24.2.4 Discontinuous Galerkin Density Functional Theory (DGDFT) 469</p> <p>24.3 DFT Implemented Computational Packages 470</p> <p>24.4 DFT as Backbone of Electronic Structure Calculations 472</p> <p>24.4.1 Design of 2D Nano-Materials 472</p> <p>24.4.2 Non-covalent Interactions and Crystal Packing 476</p> <p>24.4.3 Designing of Organic Solar Cell 477</p> <p>24.5 Concluding Remarks 480</p> <p>Acknowledgment 481</p> <p>References 481</p> <p><b>25 Structure, Stability and Bonding in Ligand Stabilized C 3 Species 491<br /> </b><i>Sudip Pan and Zhong-hua Cui</i></p> <p>25.1 Introduction 491</p> <p>25.2 Computational Details 492</p> <p>25.3 Structures and Energetics 493</p> <p>25.4 Bonding 495</p> <p>25.5 Conclusions 500</p> <p>Acknowledgements 501</p> <p>References 501</p> <p><b>26 The Role of Electronic Activity Toward the Analysis of Chemical Reactions 505<br /></b><i>Swapan Sinha and Santanab Giri</i></p> <p>26.1 Introduction 505</p> <p>26.2 Theoretical Backgrounds and Computational Details 506</p> <p>26.3 Results and Discussions 509</p> <p>26.3.1 Bimolecular Nucleophilic Substitution (S<sub>N</sub>2) Reaction 509</p> <p>26.3.2 Alkylation of Zintl Cluster 512</p> <p>26.3.3 Proton Transfer Reaction 515</p> <p>26.3.4 Water Activation by Frustrated Lewis Pairs (FLPs) 519</p> <p>26.4 Concluding Remarks 522</p> <p>Acknowledgments 522</p> <p>References 522</p> <p><b>27 Prediction of Radiative Efficiencies and Global Warming Potential of Hydrofluoroethers and Fluorinated Esters Using Various DFT Functionals 527<br /> </b><i>Kanika Guleria, Suresh Tiwari, Dali Barman, Snehasis Daschakraborty, and Ranga Subramanian</i></p> <p>27.1 Introduction 527</p> <p>27.2 Computational Methodology 528</p> <p>27.3 RE and GWP Calculation Methodology 528</p> <p>27.4 Results and Discussions 529</p> <p>27.4.1 (Difluoromethoxy)trifluoromethane (CF<sub>3</sub>OCHF<sub>2</sub>) 529</p> <p>27.4.2 Difluoro(methoxy)methane (CH<sub>3</sub>OCHF<sub>2</sub>) 529</p> <p>27.4.3 Trifluoro(methoxy)methane (CF<sub>3</sub>OCH<sub>3</sub>) 531</p> <p>27.4.4 Bis(2,2,2-trifluoroethyl)ether (CF<sub>3</sub>CH<sub>2</sub>OCH<sub>2</sub>CF<sub>3</sub>) 531</p> <p>27.4.5 1,1,1,2,2-Pentafluoro-2-Methoxyethane (CF<sub>3</sub>CF<sub>2</sub>OCH<sub>3</sub>) 534</p> <p>27.4.6 Fluoro(fluoromethoxy)methane (CH<sub>2</sub>FOCH<sub>2</sub>F) 537</p> <p>27.4.7 Methyl 2,2,2-Difluoroacetate (CHF<sub>2</sub>C(O)OCH<sub>3</sub>) 537</p> <p>27.4.8 Ethyl 2,2,2-Trifluoroacetate (CF<sub>3</sub>C(O)OCH<sub>2</sub>CH<sub>3</sub>) 537</p> <p>27.4.9 2,2,2-Trifluoroethyl 2,2,2-trifluoroacetate (CF<sub>3</sub>C(O)OCH<sub>2</sub>CF<sub>3</sub>) 540</p> <p>27.4.10 1,1-Difluoroethyl Carbonofluoridate (FC(O)OCF<sub>2</sub>CH<sub>3</sub>) 543</p> <p>27.4.11 Methyl 2,2,2-trifluoroacetate (CF<sub>3</sub>C(O)OCH<sub>3</sub>) 543</p> <p>27.5 Concluding Remarks 547</p> <p>Acknowledgment 547</p> <p>References 548</p> <p><b>28 Density Functional Theory-Based Study on Some Natural Products 551<br /> </b><i>Abhishek Kumar, Ambrish K. Srivastava, Ratnesh Kumar, and Neeraj Misra</i></p> <p>28.1 Introduction 551</p> <p>28.2 Computational Details 552</p> <p>28.3 Results and Discussion 552</p> <p>28.3.1 Geometrical Properties 552</p> <p>28.3.2 Vibrational Properties 553</p> <p>28.3.2.1 O–H Vibration 555</p> <p>28.3.2.2 C–H Vibration 555</p> <p>28.3.2.3 C–C Vibration 555</p> <p>28.3.2.4 C=O Vibration 555</p> <p>28.3.3 HOMO–LUMO and MESP Plots 555</p> <p>28.3.4 Chemical Reactivity 557</p> <p>28.4 Conclusion 558</p> <p>Acknowledgments 558</p> <p>References 558</p> <p>Index 561</p>