Transition state theory overview

We present an overview of variational transition state theory from the perspective of the dynamical formulation of the theory. This formulation provides a firm classical mechanical foundation for a quantitative theory of reaction rate constants, and it provides a sturdy framework for the consistent inclusion of corrections for quantum mechanical effects and the effects of condensed phases. A central construct of the theory is the dividing surface separating reaction and product regions of phase space. We focus on the robust nature of the method offered by the flexibility of the dividing surface, which allows the accurate treatment of a variety of systems from activated and barrierless reactions in the gas phase, reactions in rigid environments, and reactions in liquids and enzymes. 

We will first give an overview of the issues involved via a brief description of the Transition State Theory and the dynamic Grote-Hynes Theory, as developed for charge transfer reactions in solution by van der Zwan and Hynes.This will introduce the ideas of equilibrium and nonequilibrium solvation, friction and barrier recrossing. We then indicate some of the consequences and predictions for the Sfjl and Sfj2 reaction types. 

Chapter 2 is an overview of rate equations. At this point in the text, the subject of reaction kinetics is approached primarily from an empirical standpoint, with emphasis on power-law rate equations, the Arrhenius relationship, and reversible reactions (thermodynamic consistency). However, there is some discussion of collision theory and transition-state theory, to put the empiricism into a more fundamental context. The intent of this chapter is to provide enough information about rate equations to allow the student to understand the derivations of the design equations for ideal reactors, and to solve some problems in reactor design and analysis. A more fundamental treatment of reaction kinetics is deferred until Chapter 5. The discussion of thermodynamic consistency... 

The present paper is divided into two general sections, the first of which provides a brief overview of reactive scattering methods, and the second of which describes applications to specific reactive systems. The overview will be restricted to discussions on quantum reactive scattering, classical trajectory methods, and certain statistical methods such as transition state theory. Three specific reactive systems will be considered in the applications section. These are 0(3p) - - H2 -> OH + H, H(D) + H2(v=l) -> H2(DH) 4 H, and OH + H2 H2O + H. 

This review has provided an overview of the studies of pericyclic reaction transition states using density functional theory methods up to the middle of 1995. Since the parent systems for most of the pericyclic reaction classes have been studied, a first assessment of DFT methods for the calculation of pericyclic transition structures can be made. 

This volume, which is unique in its coverage, provides a general introduction to the properties and nature of transition metal carbides and nitrides, and covers their latest applications in a wide variety of fields. It is directed at both experts and nonexperts in the fields of materials science, solid-state chemistry, physics, ceramics engineering and catalysis. The first chapter provides an overview, with other chapters covering theory of bonding, structure and composition, catalytic properties, physical properties, new methods of preparation, and spectroscopy and microscopy. 

We shall in this section give a historic overview of how the electronic structure theory for transition metal complexes in their ground state has evolved from the 1950s to the present time. The account will include a discussion of wave function methods based on Hartree Fock and post-Hartree Fock approaches as well as Kohn-Sham density functional theory (KS-DFT). 

In order to be able to make reliable predictions for systems with heavy elements, an efficient relativistic theory is needed. In chapter one, Y. Ishikawa and M.J. Vilkas provide a review of multireference MoDer-Plesset (MR-MP) perturbation theory. They present a detailed overview of implementation of tiie metiiod and describe a procedure for calculating transition probabilities between the ground and excited states. The chapter is augmented by examples of relativistic MR-MP calculations of term energy separations, transition probabilities and lifetimes. 

In this chapter we present an introductory overview of the basic theoretical concepts of computational molecular photoph rsics. First, the nature and properties of electronic excitations are considered, with special attention to transition moments and vibrational contributions. Then, the main photophysical processes involving the electronic excited states are examined, focusing in particular on nonradiative deactivation phenomena. Finally, we present a brief review of computational methods commonly applied for the description of molecular excitations. Special emphasis is given to the configuration-interaction (Cl) method and the time-dependent density functional theory (TD-DFT), discussing some technical details and outlining advantages and limitations. 

In this chapter we will briefly review some topics in the theory of excited states and in computational methods for the description of molecular electronic excitations, providing a general overview of the current state of the art. For more detailed information the reader is referred to more specialized publications [2-4,12,17-32]. In particular, we will consider electronic transitions and describe the... 

---