This book begins by providing a simplified version of the computational quantum chemistry sufficient to calculate the wavefunctions that are the basic input of NG-QTAIM. Enough basic (scalar) QTAIM theory is provided to understand the later chapters. In addition, our developments of scalar QTAIM are presented and activities at various levels of difficulty are provided for the readership to facilitate understanding.
The topological origins of Quantum Theory of Atoms in Molecules (QTAIM) before explaining the highlights and consequences of the developments of Next-Generation QTAIM (NG-QTAIM) that is a 3-D vector-based realization of QTAIM. The book compiles all developments and extensions of Next-Generation QTAIM in one place for easy reference for those engaged in theoretical/computational chemistry. Essential insights into molecular switch functioning not available from the energy barrier or any scalar measures are presented along with a new measure to assess the efficiency of rotary molecular motors. The book also discusses how the treatment of external forces such as electric fields and laser irradiation is included in NG-QTAIM. This book benefits theoretical/computational chemists/physics/engineers, students (graduate and undergraduate) and chemical/pharmaceutical industry researchers who carry out chemical computations in universities and industries.
Where appropriate, Target Learning Outcomes and Further Reading are provided along with a list of the scientific goals to be addressed in addition to a glossary table in the summary sections. Where applicable each chapter concludes by outlining benefits, limitations and suggestions for further investigations.
All our NG-QTAIM publications are available as pre-prints in the form of .pdf files along with the corresponding supplementary materials at our BEACON website www.beaconresearch.org.
Author(s): Samantha Jenkins, Steven Robert Kirk
Series: Lecture Notes in Chemistry, 110
Publisher: Springer
Year: 2023
Language: English
Pages: 236
City: Singapore
Preface
References
Contents
1 Introduction to Computational Quantum Chemistry
1.1 Basis Sets Background
1.1.1 Gaussian Type Orbital (GTO) Basis Sets
1.1.2 Common Basis Set Types
1.1.3 Effective Core Potentials (ECPs) for Use with Heavy Atoms
1.1.4 Suggestions for the Choice of Basis Set
1.2 Density Functional Theory (DFT)
1.2.1 Spin Restricted and Spin Unrestricted DFT Methods
1.2.2 Wave Function Formats
1.3 Geometry Optimization
1.3.1 Normal-Mode Analysis
1.4 An Overview of the Content of the Book
1.5 Further Reading
References
2 Exploring the Topological Origins of QTAIM
2.1 The Quantum Theory of Atoms in Molecules (QTAIM): Basics
2.2 Non-euclidian Geometry for Molecules and Quantum Topology Phase Diagrams (QTPDs)
2.2.1 The Structure of Quantum Topology Phase Diagrams (QTPDs)
2.2.2 QTPDs and Non-nuclear Attractors (NNAs)
2.2.3 QTPDs and the Solid State
2.2.4 Hybrid QTAIM and Electrostatic Potential QTPDs
2.2.5 Directed QTPDs
2.3 The Number of Nearest RCPs (NNRCPs) for an Impurity NCP in a Metal Host Cluster
2.4 Determining the Presence of Covalent Character in Closed-Shell Bonding
2.5 A Measure of Metallic Character: Metallicity ξ(rb), Polarizability P and Stiffness S
2.6 Summary
2.7 Further Reading
References
3 Bridging Scalar QTAIM and Vector-Based Next Generation QTAIM
3.1 Relating the Projected Density of States (PDOS) and QTAIM
3.2 The Bond-Path Framework: Lack of Accordance of the Motion of ρ(rb) and Nuclei for Bond Torsion
3.2.1 Torsion of Biphenyl: Detachment and Reattachment of the Bond-Path Framework
3.2.2 The Photo-Isomerization of the Retinal Chromophore
3.2.3 The QTAIM Interpreted Ramachandran Plot
3.2.4 Explanation of the (βϕ-βψ) and (βϕ*-βψ*) of the Closed-Shell H--O/H---O BCPs and H---H BCPs
3.3 Summary
3.4 Further Reading
References
4 The NG-QTAIM Interpretation of the Chemical Bond
4.1 Construction of the Bond-Path Framework Set: Vector-Based Representation of the Chemical Bond
4.2 Construction of the Precession K of the Bond-Path Framework Set B
4.3 Applications of the Bond-Path Framework Set: Normal Modes of Vibration
4.3.1 3-D Bonding Morphology of the Infra-Red Active Modes of Benzene
4.3.2 A Vector-Based Representation of the Chemical Bond for the Normal Modes of Benzene
4.3.3 Bond Flexing, Twisting, Anharmonicity and Responsivity for the IR-Active Modes of Benzene
4.4 Strained and Unusual Bonding Environments
4.4.1 The Directional Bonding of [1.1.1] Propellane
4.5 Multi-electronic States
4.5.1 Ring-Restoring Reactions
4.5.2 The Excited State Deactivation Reaction of Fulvene
4.5.3 Factors Influencing the Relative Stability of the Conical Intersections of the Penta-2,4-Dieniminium Cation (PSB3)
4.6 Summary
4.7 Further Reading
References
5 The Stress Tensor σ(r) and Ehrenfest Force F(r)
5.1 The Stress Tensor σ(r)
5.1.1 The Stress Tensor σ(r) Bond-Path Framework Set Bσ
5.1.2 Halogen and Hydrogen-Bonding in Halogenabenzene/NH3 Complexes Compared
5.1.3 Photochemical Reaction Path from Benzene to Benzvalene
5.2 The Ehrenfest Force F(r): A Physically Intuitive Approach for Analyzing Chemical Interactions
5.2.1 The Ehrenfest Force F(r) with Lithium
5.2.2 The Ehrenfest Force F(r) Bond-Path Framework Set BF, BσF and BσHF
5.3 The Precessions KʹF and KF Corresponding to the Ehrenfest Force F(r)
5.3.1 Precessions KʹF and KF of the Ehrenfest Force F(R) for the Unusual Strength of Hydrogen-Bonding
5.4 Summary
5.5 Further Reading
References
6 The Eigenvector-Space Trajectories for Symmetry Breaking
6.1 Theoretical Background of the Eigenvector-Space Trajectories Ti(s); i = {σ, ρ, F}
6.2 Numerical Considerations for Construction of the Eigen-Space Trajectories Ti(s); i = {σ, ρ, F}
6.2.1 The QuantVec Program Package
6.3 Applications of the Eigenvector-Space Trajectories Ti(s); i = {ρ}: the Hessian of ρ(r) Trajectory T(s)
6.3.1 Normal Modes of Vibration: Isotope Effects and Bond Coupling
6.4 Applications of the Eigenvector-Space Trajectories Ti(s); i = {σ}: the Stress Tensor Trajectory Tσ(s)
6.4.1 Normal Modes of Vibration and Dynamic Coupling
6.4.2 Covalent (Sigma) OH and Hydrogen-Bond Coupling on the (H2O)5 MP2 Potential Energy Surface
6.4.3 Iso-Energetic Phenomena I: Prediction of the Flip Rearrangement in the Water Pentamer
6.4.4 Iso-Energetic Phenomena II: Torquoselectivity in Competitive Ring-Opening Reactions
6.5 Applications of the Eigenvector-Space Trajectories Ti(s); i = {F}: Ehrenfest Force F(r) TF(s)
6.5.1 Determining Photochemical Ring-Opening Reactions of Oxirane with the Ehrenfest Force F(r)
6.6 Summary
6.7 Further Reading
References
7 Stereochemistry Beyond Chiral Discrimination
7.1 Insufficiency of Scalar Measures for Chiral Discrimination
7.1.1 Location of the Unknown Helical Character Associated with Chirality
7.1.2 Inducing the Required Symmetry-Breaking to Reveal Helical Character
7.2 First Generation Stress Tensor Trajectories Tσ(s)
7.2.1 The Choice of the Stress Tensor Trajectory Tσ(s) for Chiral Discrimination
7.3 Refinements of the First Generation Stress Tensor Trajectories Tσ(s)
7.3.1 Hydrogen and Deuterium Isotopomers of Glycine Compared
7.3.2 Subjecting Glycine to an Electric (E)-Field
7.3.3 The Chirality-Helicity Function Chelicity for Cumulenes
7.3.4 The Chirality with Stereoisomers for SN2 Reactions
7.4 Second Generation Stress Tensor Trajectories Tσ(s)
7.4.1 Chiral and Steric Effects in Ethane
7.4.2 Mixed Chiral and Achiral Character in Substituted Ethane
7.4.3 Controlling Achiral and Chiral Properties of Alanine with an Electric Field
7.4.4 Explanation of Why the Cis-Effect is the Exception and Not the Rule
7.5 Summary
7.6 Further Reading
References
8 The Design of Molecular Devices
8.1 Steering Molecular Devices: With Vector-Based Measures
8.2 Controlling Molecular Rotary Motors
8.3 Switches: ‘ON’ and ‘OFF’ Mechanisms: Hydrogen Transfer Tautomerization
8.3.1 Deformation of a Nuclear Skeleton via Hydrogen Atom Sliding
8.3.2 E-Fields for Improved “ON” and “OFF” Switch Performance
8.4 Switches: Ring-Opening Reactions
8.5 Fatigue of Photo-Switches
8.5.1 Photo-Switch Fatigue Response to External Fields Electric(E)-Fields
8.6 Assembly of Electronic Devices Using Molecules
8.6.1 Scoring Molecular Wires in E-fields for Molecular Electronic Devices
8.6.2 Design of Emitters Exhibiting Thermally-Activated Delayed Fluorescence (TADF)
8.6.3 Effect of a Static E-field on the Energy Gap ΔE(S1-T1)
8.6.4 Manipulation of the Energy Gap ΔE(S1-T1) with Laser Pulses
8.7 Summary
8.8 Further Reading
References
Appendix A
Appendix B
Mathematical Derivations
Index
