Theoretical and Computational Photochemistry: Fundamentals, Methods, Applications and Synergy with Experimental Approaches

Cover
Half Title
Theoretical and Computational Photochemistry: Fundamentals, Methods, Applications and Synergy with Experimental Approaches
Copyright
Contents
Contributors
Preface
Part I. Fundamentals
	1. Introduction to molecular photophysics
		1.1. Interaction between electromagnetic radiation and molecules
			1.1.1. Electromagnetic radiation
			1.1.2. Time-dependent perturbation theory: A tool for describing the matter-radiation interaction
			1.1.3. Electric dipole transitions
			1.1.4. Spontaneous emission
		1.2. Quantization of energy
		1.3. The Franck-Condon principle
		1.4. Electronic absorption spectra
			1.4.1. Transition energy
			1.4.2. Transition intensity: The oscillator strength and the transition dipole moment
			1.4.3. Absorption band shape: The dynamic effect and the vibronic coupling
			1.4.4. Multiphotonic absorption
		1.5. Fluorescence and phosphorescence emission
			1.5.1. Fluorescence
				1.5.1.1. Fluorescence spectrum
				1.5.1.2. Kashas rule
				1.5.1.3. Fluorescence lifetime and quantum yield
				1.5.1.4. Fluorescence quenching
				1.5.1.5. Factors influencing fluorescence
				1.5.1.6. Steady-state vs time-resolved fluorescence
				1.5.1.7. Anti-Stokes photon emission
			1.5.2. Phosphorescence
				1.5.2.1. Phosphorescence from doublet and quartet states
		References
	2. Theoretical grounds in molecular photochemistry
		2.1. The Jablonski diagram
		2.2. Potential energy surfaces and reaction paths
		2.3. The Born-Oppenheimer approximation in detail: Adiabatic and diabatic representations
			2.3.1. Separation of nuclei and electrons motion
			2.3.2. Adiabatic representation
			2.3.3. Diabatic representation
		2.4. When potential energy surfaces do cross: Avoided crossings and conical intersections
		2.5. Excited state molecular dynamics
		References
Part II. Methods
	3. Density-functional theory for electronic excited states
		3.1. Overview
		3.2. Linear-response (``time-dependent´´) DFT
			3.2.1. Theoretical formalism
				3.2.1.1. Linear-response theory
				3.2.1.2. Adiabatic approximation
				3.2.1.3. Tamm-Dancoff approximation
				3.2.1.4. Analytic gradients
			3.2.2. Performance and practice
				3.2.2.1. Restriction of the excitation manifold
				3.2.2.2. Exchange-correlation functionals
				3.2.2.3. Accuracy for vertical excitation energies
				3.2.2.4. Visualization
			3.2.3. Systemic problems
				3.2.3.1. Description of charge transfer
				3.2.3.2. Conical intersections
		3.3. Excited-state Kohn-Sham theory: The DeltaSCF approach
			3.3.1. Theory
				3.3.1.1. General considerations
				3.3.1.2. Orbital-optimized non-aufbau SCF solutions
				3.3.1.3. Transition potential methods
			3.3.2. Examples
		3.4. Time-dependent Kohn-Sham theory: ``Real-time´´ TDDFT
			3.4.1. Theory
			3.4.2. Examples
		References
	4. Algebraic diagrammatic construction schemes for the simulation of electronic spectroscopies
		4.1. Introduction
		4.2. Theoretical background
			4.2.1. Intermediate-state representation
			4.2.2. State properties and geometries
			4.2.3. The physical meaning of ISR basis states and EE-ADC matrix elements
			4.2.4. Relation of different ADC schemes
		4.3. Comparison of ADC to configuration interaction and coupled cluster methods
		4.4. ADC variants for excited states
			4.4.1. Semiempirical EE-ADC schemes
			4.4.2. EE-ADC schemes for multireference systems
			4.4.3. EE-ADC methods for X-ray spectroscopies
		4.5. Computational spectroscopy in complex environments with ADC
		4.6. Computational photochemistry with ADC
		4.7. Outlook and concluding remarks
		References
	5. Multiconfigurational quantum chemistry: The CASPT2 method
		5.1. Introduction
		5.2. Prelude: CASSCF
		5.3. CASPT2 theory
			5.3.1. CASPT2 fundamentals
				5.3.1.1. The H0 operator
				5.3.1.2. Defining the first-order interacting space
				5.3.1.3. Computing the first-order interacting space and the second-order energy
			5.3.2. The intruder state problem
			5.3.3. Shift techniques
			5.3.4. Alternative selection of the zeroth-order Hamiltonian
				5.3.4.1. CASPT2 applied to an open-shell system
				5.3.4.2. The gi family of corrections
				5.3.4.3. The IPEA shift
				5.3.4.4. Use of Koopmans matrices, CASPT2-K
				5.3.4.5. The zeroth-order Hamiltonians of Dyall and Fink
				5.3.4.6. Summary
		5.4. Multistate CASPT2 theory
		5.5. Performance
		5.6. Future developments
		5.7. Summary and conclusions
		References
	6. Machine learning methods in photochemistry and photophysics
		6.1. Introduction
		6.2. Machine learning models
			6.2.1. Machine learning tasks
			6.2.2. k-Nearest neighbor
			6.2.3. Support vector machine
			6.2.4. Kernel methods
			6.2.5. Neural networks
		6.3. Representations of molecules
			6.3.1. Molecular strings and fingerprints
			6.3.2. Molecular descriptors
			6.3.3. Automatically generated descriptors
		6.4. Training data for machine learning
			6.4.1. Excited-state database across chemical space
			6.4.2. Molecule-specific data generation
		6.5. Applications of machine learning in photochemistry and photophysics
			6.5.1. Machine learning-assisted high-throughput virtual screening
			6.5.2. Machine learning-predicted electronic spectroscopy
			6.5.3. Machine learning nonadiabatic molecular dynamics
			6.5.4. Machine learning-extracted chemical insights from data
		6.6. Summary
		References
	7. Polaritonic chemistry
		7.1. Preliminary considerations on the electromagnetic field
		7.2. Polaritonic eigenvalues and eigenstates
			7.2.1. Cavity Born-Oppenheimer and vibrational strong coupling
			7.2.2. Electronic strong coupling (ESC)
		7.3. Polaritonic potential energy surfaces (PoPESs)
			7.3.1. A didactical case: Azobenzene polaritonic potential energy surfaces (PoPESs)
			7.3.2. Many molecules and dark states
		7.4. Polariton dynamics and cavity losses
			7.4.1. Nuclear dynamics in polaritonic systems: Full quantum vs semiclassical
		7.5. Summary
		References
Part III. Applications
	8. First-principles modeling of dye-sensitized solar cells: From the optical properties of standalone dyes to the ...
		8.1. Introduction
		8.2. Computational modeling of DSSCs: Methods, limitations, and practical strategies
			8.2.1. Generalities
			8.2.2. Electronic structure and optical properties of dyes in solution
			8.2.3. Electronic structure and optical properties of semiconductor materials and dye-sensitized interfaces
			8.2.4. Machine learning and semiempirical methods applied to DSSCs
		8.3. Design rules for Ru(II) sensitizers: The role of spin-orbit coupling (SOC)
		8.4. Modeling the photophysics of Fe(II) metal complexes: Tools and findings
		8.5. Interfacial properties of Fe-NHC-sensitized TiO2
		8.6. Conclusions
		References
	9. Solar cells: Organic photovoltaic solar cells
		9.1. Introduction
			9.1.1. Organic photovoltaics
			9.1.2. OPV materials
			9.1.3. Models to describe charge generation in OSCs
		9.2. Excitonic processes: Excited states at the donor/acceptor interfaces
			9.2.1. Electronic structure methods to describe the excited states at D/A OPV interfaces
			9.2.2. Analytical tools to characterize the excited-state wavefunction
			9.2.3. Examples of polymer/fullerene OPV interfaces
		9.3. Time-dependent processes: Excited-state dynamics in donor and donor/acceptor domains
			9.3.1. Excited-state dynamics: Brief overview of nonadiabatic surface hopping and multiconfiguration time-dependent Hartr ...
			9.3.2. Excited-state dynamics of oligothiophenes as prototypes for P3HT
			9.3.3. Examples of polythiophene-/fullerene-based interfaces
		9.4. Conclusions
		References
	10. Perovskite-based solar cells
		10.1. Introduction
		10.2. First-principles modeling of perovskites
		10.3. Point defects in perovskites
			10.3.1. First-principles modeling of point defects
			10.3.2. Ion migration in perovskite
			10.3.3. Photochemistry of iodine Frenkel defects
		10.4. Interfaces in perovskite solar cells
			10.4.1. Understanding charge extraction at the perovskite/ETL interface
			10.4.2. Chemical tuning of the perovskite/HTL interface
		10.5. Degradation and passivation of metal-halide perovskites
			10.5.1. Water-induced degradation of lead-halide perovskites
			10.5.2. Instability of lead-free perovskites in water environment
			10.5.3. Perovskite surface passivation
		10.6. Summary
		References
	11. Thermally activated delayed fluorescence
		11.1. Introduction
		11.2. Excited states calculations
		11.3. Condensed phase effects
		11.4. Role of charge transfer and local excited states
		11.5. Vibronic effects and rate calculations
		11.6. Synopsis
		References
	12. DNA photostability
		12.1. Photophysics of canonical nucleobases in the gas phase. Photostability
			12.1.1. Absorption properties in the gas phase
			12.1.2. Photophysical paths for purine nucleobases
			12.1.3. Excited-state dynamics of purine nucleobases
			12.1.4. Photophysical paths for pyrimidine nucleobases
			12.1.5. Excited-state dynamics of pyrimidine nucleobases
		12.2. Photophysics of canonical nucleobases in solution. Impact of the solvent effects into the photostability
			12.2.1. Purine nucleobases
				12.2.1.1. Absorption spectra
				12.2.1.2. Photophysical paths
				12.2.1.3. Excited-state dynamics
			12.2.2. Pyrimidine nucleobases
				12.2.2.1. Absorption spectra
				12.2.2.2. Photophysical paths
				12.2.2.3. Excited-state dynamics
		12.3. Photophysics of modified nucleobases. Impact of the substitution effects into the photostability
			12.3.1. Addition of external groups into the pyrimidine/purine core
				12.3.1.1. Methylation (CH3)
				12.3.1.2. Amination (NH2)
				12.3.1.3. Oxo incorporation (CO)
				12.3.1.4. Other groups
			12.3.2. Substitution of internal groups into the pyrimidine/purine core
				12.3.2.1. Oxygen-by-sulfur or carbon-by-sulfur substitution
				12.3.2.2. Carbon-by-nitrogen or nitrogen-by-carbon substitutions
		12.4. Photophysics of canonical nucleobases in DNA/RNA environments. Photostability mechanisms
			12.4.1. Single monomers embedded in a DNA/RNA environment
			12.4.2. DNA/RNA light absorption and excited-state delocalization
			12.4.3. Watson-Crick base pairing and interstrand charge transfer states. A doorway to proton transfer and photostability
		12.5. Final remarks and future perspectives
		References
	13. Fluorescent proteins
		13.1. Introduction
		13.2. Modeling of absorption spectra
		13.3. Frster resonance energy transfer
		13.4. Photochemical reactions
		13.5. Concluding remarks
		References
	14. Chemi- and bioluminescence: A practical tutorial on computational chemiluminescence
		14.1. Introduction
		14.2. Design of the methodology
		14.3. Identification of the molecule responsible for chemiexcitation
			14.3.1. Walsh correlation diagrams
			14.3.2. Reaction paths for the chemiexcitation of small models
			14.3.3. ``Activator´´-``chemiluminophore´´ configuration
		14.4. Reaction paths of the isolated system
			14.4.1. Formation of the chemiluminophore
			14.4.2. Chemiexcitation
			14.4.3. Light emission
			14.4.4. Identification of relevant parameters in challenging systems
		14.5. Solvent effects
		14.6. Dynamical aspects
		14.7. A perspective on future research directions
		References
	15. Chemi- and bioluminescence: Bioluminescence
		15.1. Introduction
		15.2. Bioluminescence, a reaction scheme of a chemiluminescent system catalyzed by a protein: Challenges for theoretical  ...
			15.2.1. Overview of a bioluminescent process
			15.2.2. Generation of HEI
			15.2.3. Decomposition of HEI to the light emitter
			15.2.4. Emission of light
		15.3. Tools and choices of the theoretical chemist: Divide to conquer
			15.3.1. Performing calculation of a small chemiluminescent model in vacuum
			15.3.2. Performing calculation of a chemiluminescent model in the solvent
			15.3.3. Performing calculation of a bioluminescent model in the protein
				15.3.3.1. Completing the protein
				15.3.3.2. Docking the ligand in the protein
				15.3.3.3. Getting the force field parameters for the substrate
				15.3.3.4. Relaxing the structure
				15.3.3.5. QM/MM calculations
			15.3.4. Modeling spectral shape
		15.4. Modeling formation of HEI: Case of firefly bioluminescent system
			15.4.1. From d-luciferin substrate to d-luciferyl adenylate intermediate
			15.4.2. Approach of dioxygen to the d-luciferyl adenylate intermediate
			15.4.3. Deciphering between reaction schemes for the reaction of dioxygen with the d-luciferyl adenylate intermediate
			15.4.4. Formation of the dioxetanone ring: Addition-elimination mechanism?
		15.5. Modeling decomposition of HEI leading to the light emitter in firefly
			15.5.1. Failure of small models
			15.5.2. Model in vacuum
			15.5.3. Model in proteins
		15.6. Modeling light emission
			15.6.1. Challenges in modeling and experiments
			15.6.2. Nature of the light emitter of firefly: The oxyluciferin
			15.6.3. Use of analogs of firefly oxyluciferin
			15.6.4. Influence of the protein on the emitted light color
			15.6.5. Example of one mutation in luciferase
			15.6.6. Different colors in different luciferases
			15.6.7. Modeling emission spectra for substrate analogs
		15.7. Conclusion
		References
	16. Photocatalysis
		16.1. Introduction and historical overview
		16.2. Fundamental mechanism of heterogeneous photocatalysis
			16.2.1. Light absorption and photoexcitation
			16.2.2. Charge migration and recombination
			16.2.3. Photoredox reactions
		16.3. Brief overview of computational methodologies
			16.3.1. Kohn-Sham density functional theory (KS-DFT)
			16.3.2. Multireference and multiconfigurational methods
			16.3.3. Combined quantum mechanical and molecular mechanical (QM/MM) methods
		16.4. Computational studies
			16.4.1. TiO2
			16.4.2. ZnO
			16.4.3. MoS2
			16.4.4. UiO-66
			16.4.5. PCN-601
			16.4.6. g-C3N4
		16.5. Outlook
		References
	17. Nonlinear spectroscopies
		17.1. Introduction
		17.2. Basic concepts
			17.2.1. Introduction to the Liouville space
			17.2.2. The displaced Brownian oscillator model
			17.2.3. Including solvent effects through energy-gap correlation functions
		17.3. Linear absorption
			17.3.1. Linear spectroscopy in the Liouville space
				17.3.1.1. Spectral lineshapes in linear absorption
			17.3.2. The nuclear ensemble approach
				17.3.2.1. Automated NEA broadenings with machine learning
		17.4. Nonlinear spectroscopy
			17.4.1. Nonlinear spectroscopy in the Liouville space
			17.4.2. Nonlinear spectroscopies within a static approximation
				17.4.2.1. The nuclear ensemble approach to nonlinear spectroscopy
			17.4.3. Spectral broadenings in nonlinear spectroscopies
				17.4.3.1. Time-resolved NEA approach to nonlinear spectroscopy
		17.5. Overview
		References
	18. Mechano-photochemistry
		18.1. Introduction
		18.2. Mechanochemical models
		18.3. Methodology and models in mechano-photochemistry
			18.3.1. Absorption and emission tuning
			18.3.2. Triplet energy transfer modulation
			18.3.3. Mechanical effect on conical intersections/avoided crossings
			18.3.4. Non-adiabatic molecular dynamics with explicit inclusion of mechanical external forces
			18.3.5. Substituent effect as mechanical entity
		18.4. Mechanical control of molecular photophysics and photoreactivity
			18.4.1. Excitation energy
				18.4.1.1. Complete mechanochemical control of the absorption spectrum
				18.4.1.2. Mechanochemical control of absorption spectrum in photoswitches
			18.4.2. Mechanochemical control of photochemical reactivity
				18.4.2.1. Mechanical control of trans-cis photoisomerization quantum yield
				18.4.2.2. Mechanical control of photoswitches in molecular solar thermal energy storage systems
				18.4.2.3. Mechanical control of photoswitching of stilbenes with molecular force probes
				18.4.2.4. Mechanical control of triplet-sensitized oxa-di-π-methane rearrangement
		18.5. Conclusions and perspectives
		References
Part IV. Synergy with experimental approaches
	19. Interplay between computations and experiments in photochemistry
		19.1. Introduction
		19.2. Correlation between the principal experimental techniques used in photochemistry and computational methods
			19.2.1. UV-Vis spectroscopy
			19.2.2. Photoluminescence spectroscopy, fluorescence, and phosphorescence
			19.2.3. Time-resolved spectroscopy and transient absorption spectroscopy (TAS)
			19.2.4. Other techniques
		19.3. Different case studies combining theory and experiments
			19.3.1. Design of new sunscreens by computational methods
			19.3.2. Spectroscopic characterization of different families of photoswitches
			19.3.3. Better understanding time-resolved spectroscopy
			19.3.4. Two-photon absorption
		19.4. Conclusions
		References
Index
Cover back