Photochemistry theory

Leifer, A., The Kinetics of Environmental Aquatic Photochemistry Theory and Practice, American Chemical Society Professional Reference Book, Washington DC,... 

Leifer, A. 1988. The kinetics of environmental aquatic photochemistry theory and practice. American Chemical Society, Washington, DC. 

To use direct dynamics for the study of non-adiabatic systems it is necessary to be able to efficiently and accurately calculate electronic wave functions for excited states. In recent years, density functional theory (DFT) has been gaining ground over traditional Hartree-Fock based SCF calculations for the treatment of the ground state of large molecules. Recent advances mean that so-called time-dependent DFT methods are now also being applied to excited states. Even so, at present, the best general methods for the treatment of the photochemistry of polyatomic organic molecules are MCSCF methods, of which the CASSCF method is particularly powerful. 

Being able to ntn direct dynamics calculations will add an extra, important, tool to help chemists understand photochemical systems. This chapter has outlined the present standpoint of the theory and practice of such calculations showing that, although much work remains to be done, they are already bringing new insight to mechanistic studies of photochemistry. 

The first three chapters discuss fundamental bonding theory, stereochemistry, and conformation, respectively. Chapter 4 discusses the means of study and description of reaction mechanisms. Chapter 9 focuses on aromaticity and aromatic stabilization and can be used at an earlier stage of a course if an instructor desires to do so. The other chapters discuss specific mechanistic types, including nucleophilic substitution, polar additions and eliminations, carbon acids and enolates, carbonyl chemistry, aromatic substitution, concerted reactions, free-radical reactions, and photochemistry. 

Lamola, A. A. (1969). Electronic energy transfer in solutions theory and application. In Leermakers, P. A., and Weissberger, A. (eds.), Energy Transfer and Organic Photochemistry, Technique of Organic Chemistry 14 17-132. Interscience Publishers, New York. 

An excited state of a molecule can be regarded as a distinct chemical species, different from the ground state of the same molecule and from other excited states. It is obvious that we need some method of naming excited states. Unfortunately, there are several methods in use, depending on whether one is primarily interested in photochemistry, spectroscopy, or MO theory." One of the most common methods... 

The assignment of the TR spectra were based on the known photochemistry of the aryl azides and comparison of the TR spectra vibrational frequencies to those predicted by density functional theory calculations for the likely photochemical intermediates. The good agreement between the experimental TR vibrational... 

In order to computationally study these processes it is crucial to be able to model the radiationless nonadiabatic transitions. It is growth in this area that has catalyzed computational photochemistry and photobiology. The basics of the theory describing radiationless transitions are outlined below. 

An extremely interesting question in the photochemistry of interstellar molecules concerns the size at which classes of molecules become resistant to the interstellar radiation field. Up to now, only statistical theories have been brought to bear on the question (see below).83 115... 

Perturbative methods (CASPT2 [17], NEVPT2 [18]) add the dynamical correlation in an effective way, using multiconfigurational second-order perturbation theory on the CASSCF input states. These methods have proved to be suitable for studying problems in spectroscopy, photochemistry, and so on [19, 20]. 

Single coordinate model, molecular photochemistry, 493-496 Single-surface nuclear dynamics geometric phase theory, 23-31... 

The present volume deals with the properties of dienes, described in chapters on theory, structural chemistry, conformations, thermochemistry and acidity and in chapters dealing with UV and Raman spectra, with electronic effects and the chemistry of radical cations and cations derived from them. The synthesis of dienes and polyenes, and various reactions that they undergo with radicals, with oxidants, under electrochemical conditions, and their use in synthetic photochemistry are among the topics discussed. Systems such as radialenes, or the reactions of dienes under pressure, comprise special topics of these functional groups. 

The two simple theories SCT and TST have been developed in the context of neutral gas-phase reactions. In this section, we consider other types of elementary reactions listed in Section 6.2.1, and include reactions in condensed phases. The rates of this diverse set of reactions, including photochemistry, can be understood with the concepts developed for gas-phase reactions. 

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