Contents -- Preface -- Chapter 1. Introduction to Magnetism -- Historical Preamble and Significance of Magnetism -- Definitions -- Quantum Theory of Diamagnetism and Paramagnetism -- Diamagnetism -- Paramagnetism -- Van Vleck paramagnetism -- Pauli paramagnetism -- Ferromagnetism and Antiferromagnetism -- Antiferromagnetic susceptibility -- Ferromagnetic susceptibility -- Exchange Hamiltonian for a ferromagnet -- Magnons -- Organic Radicals -- References -- Chapter 2. Organic Molecules, Radicals, and Spin States -- Organic Monoradicals -- Diradicals -- Intramolecular Interaction and Predicting the Spin State of Diradicals -- An Alternative View of Spin State Preference -- Polyradicals -- Hamiltonian for Organic Diradicals -- From Molecules to Materials -- Early Discoveries of Organic Ferromagnetic Systems -- Intermolecular Interaction and Ferromagnetism in Extended Systems -- Molecular Design and Molecular Magnets -- Experimental Methods for Triplets -- References -- Chapter 3. Theoretical Methodologies -- Mean-Field Approximation -- SCF methodology -- R(O)HF -- UHF -- Post-Hartree-Fock Treatments -- Electron correlation -- Configuration interaction -- Many-body perturbation theory -- Multi-configuration approaches -- Coupled-cluster approach -- Discussion -- Density Functional Theory (DFT) -- Thomas-Fermi model -- Hohenberg-Kohn theorems -- Kohn-Sham methodology -- Exchange-correlation functionals -- The B3LYP methodology for low-lying open-shell states -- Discussion -- Broken Symmetry Methodology -- Concluding Remarks -- References -- Chapter 4. Molecular Orbital Description of Magnetic Organic Systems -- Properties of the Single Determinant and the Dissociation Problem2 -- General MO Description of Diradicals -- Cyclobutadiene -- Trimethylene methane -- Parabenzyne Diradicals -- Metabenzyne.

Metaphenylene Bismethylene (Metaxylylene) Diradicals -- Metaphenylene and Paraphenylene Coupling of -NHO Radicals -- Generalizations -- Advanced Methods for Diradicals -- Reconciling DFT Methods with the Multi-Configurational Character of Diradicals -- Advanced Correlation-Corrected Descriptions of Dissociation -- Correlation Corrections and the Singlet-Triplet Gap in Diradicals: MP2 Add-Ons -- Brueckner Doubles -- DDCI and an Approximation -- Use of BSS MOs as a Starting Place for Coupled-Cluster Corrections -- The Spin-Flip Methods -- Conclusions -- References -- Chapter 5. Qualitative Methods for Predicting Molecular Spin States -- Introduction -- A Few Remarks on Hund's Rule(s) -- Alternant Hydrocarbons and Nonbonded Levels -- Spin Multiplicity in Alternant Organic Molecules with Conjugated Bonds -- Spin Alternation: An Illustration from Unrestricted Calculations -- Spin Alternation in Unrestricted SCF Ground State -- Disjoint Orbitals and the Possibility of Hund's Rule Violations -- Spin Control: Dougherty's Non-Kekule Acenes -- Geometrical Distortion and Failure of Topological Rules -- Can the rules be overturned? Nonplanarity and inefficient pi coupling -- Are the rules robust? -- Polyradicals and Topology -- Multiple Phenylene Couplers -- New Design Elements: Heterosubstitution and Net Charge -- Toward Materials: Larger Molecules, Chains, and Higher Dimensions -- Intermolecular Ferromagnetic Coupling: Evaluation of McConnell Mechanism I -- Evaluation of McConnell's Second Mechanism for Intermolecular Ferromagnetic Coupling -- Kollmar and Kahn's analysis of McConnell II -- A serious experimental test of the McConnell charge-transfer theme -- Real Solid Organic Ferromagnets? -- A low-temperature organic ferromagnet -- A room-temperature organic ferromagnet -- Concluding Remarks -- References.

Chapter 6. Quantum Chemical Calculations: Structural Trends -- General Trends of Electronic Structure Calculations -- Two Case Studies: Diradicals TMM and TME -- Coupled Radicals -- Linear Couplers: Unsaturated Hydrocarbon Chains -- Aromatic Couplers -- NN diradicals -- Other cyclic diradicals -- Are triplets favored when the SOMO-SOMO energy gap is small? -- Is the Hay-Thibeault-Hoffmann formula general? -- Is disjoint character of SOMOs unambiguous? -- Fused-ring couplers -- Polyacene couplers -- Mixed Couplers: Molecular Tailoring -- Example 1: Diphenylene-acetylene couplers -- Example 2: TMM analogues -- Example 3: Refinement of the fused-ring design in TMM analogues -- Discussion: Aids to our Understanding -- Spin density plot -- Nucleus-independent chemical shift (NICS) -- The hyperfine coupling constant (HFCC) -- Solvent effect -- Strength of radical centers -- Summary -- References -- Chapter 7. Strongly Coupled Magnetic Molecules -- Secrets of Design -- Strong Ferromagnetic Coupling -- NN-nC-oVER(N) -- NN-even-TTF -- NN-pyrene-o-VER(N) -- Aminoxyl diradicals -- Schlenk diradicals -- Substitution effect -- Planarity -- Tests for Confirmation -- NN-nC-o-VER(C) -- NN-odd-TTF -- NN-pyrene-o-VER(C) -- Diradical Characteristics -- Diradical character I (the parameter 2σ) -- Diradical character II (the parameter R) -- Diradical nature III (the parameter N) -- Canonical components analysis of spin and charge density in diradicals -- Spin components -- Charged structures -- References -- Chapter 8. Photomagnetic Effects -- Introduction -- Spin Crossover - An Important Development from Inorganic Chemistry -- Vibrational properties -- Theoretical and computational front -- Photochromism - An Exotic Phenomenon in Organic Chemistry -- Photomagnetism - A Futuristic Phenomenon for Materials Science -- The CPD-DHP Coupler Pair.

Calculated and Observed Spectrum -- Cis- and Trans-photoconversion of Azobenzene Derivatives -- Photomagnetic Effect in Stilbene-Based Diradicals -- Spin alternation -- Photochromism -- Photomagnetism -- Photomagnetic Molecular Devices -- Excited state magnetism -- Photochromism and materials -- Conclusions -- References -- Chapter 9. Transition Metal Complexes -- Introductory Remarks -- Spin Hamiltonians and Magnetic Coupling in Transition Metal Complexes -- The Heisenberg-Dirac-Van Vleck Hamiltonian -- Ising Model -- Beyond the HDVV Hamiltonian: The Hubbard Hamiltonian -- The Mapping Procedure: Linking Ab initio Calculations and Parameters of Low-Dimension Hamiltonian -- Beyond the Mapping Procedure: Effective Hamiltonian Theory -- What Needs to be Captured in the Effective Hamiltonian? -- On the Need for Highly Accurate Calculations -- UHF and DFT Methods: BS Open-Shell Calculations -- References -- Chapter 10. Computational Studies of Inorganic Clusters and Solid Systems -- Choice of Methods1 -- Inorganic Clusters -- Magnetic Solids with Localized Spin Moments -- Applications to Periodic Systems -- Selected Case Study Examples: Extended Systems -- Concluding Remarks -- References -- Chapter 11. A Look Ahead -- An Organic Chemist's Coup -- Silicon Chains with Oxo-verdazyl Pendant -- Desiderata for Materials to be Used for Spintronics -- Molecular solids and single-molecule junctions -- Ferrocenes and related systems -- Polyferrocenylsilane-based polymers and a modest proposal -- Graphene as a Spin Filter -- Rajca's Polyradicals and a Modest Proposal -- Final Remarks -- References -- Index.