The authors introduce the concept of Molecular Quantum Similarity, dev eloped in their laboratory, in a didactic form. The basis of the conce pt combines quantum theoretical calculations with molecular structure and properties even for large molecules. They give definitions and pro cedures to compute similarities molecules and provide graphical tools for visualization of sets of molecules as n-dimensional point charts.

In this chapter ve shall discuss the calculation of potential energy associated vith molecular conforaations. Raving obtained cartesian atoaic coordinates defining conforaations. and lists of intraao- cular interactions, as described in Chapter 3, ve are ready to calculate a quantity which in the chemical literature is known as the total aolecular potential energy or the conforaational, steric, strain or intraaolecular energy. ~he conformational energy of a aolecule can be expressed as a function , of all internal coordinates and interatoaic distances, or as a function of atoaic positions...

One should distinguish between coordination numbers and hydration numbers. Following Bockris

Introduction 1 1. 2. Basic Concepts and Phenomenological Description 6 2.1. Separation of the Center-of-Mass Motion 8 2.2. Separation of Electronic and Nuclear Motions. Interaction Potentials (Potential-Energy Surfaces) 11 2.2.1. Heuristic Considerations 11 2.2.2. Born-Oppenheimer Separation. Adiabatic Approximation, 16 Present State of Potential-Energy-Burface 2.2.3. Calculations 23 2.3. Scattering Channels 6 2.4. Classification of Elementary Processes. Microscopic Mechanism 27 D.ynamics of Atomic and Molecular Collisions: 3. Electronically Adiabatic Processes 32 Classical Approach 3.1. 33...

I I These Lecture Notes are intended as an introduction to the theoretical formulation and computational aspects of the molecular energy transfer processes which take place in an increasingly sophisticated range of molecular scattering experiments. They are directed to chemistry graduate students and emphasize the quantum mechanical approach, with little or no attention to classical and semi- classical treatments or to formal presentations. Several Sections of the first Chapters are based on lectures given at the Graduate School of Physics of the University of Genoa a few years ago and I...

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Since the discovery of quantum mechanics, more than fifty years ago, the theory of chemical reactivity has taken the first steps of its development. The knowledge of the electronic structure and the properties of atoms and molecules is the basis for an un- derstanding of their interactions in the elementary act of any chemical process. The increasing information in this field during the last decades has stimulated the elaboration of the methods for evaluating the potential energy of the reacting systems as well as the creation of new methods for calculation of reaction probabili- ties (or...

A wide range of important physical and chemical phenomena may be named by the same title: Rate processes in condensed media. They have the same underlying physics and mathematics. To these phenomena belong: 1) Small polaron motion [a] 2) Electron transfer between ions in solutions [b] and in photosynthetic centers [c]. 3) Electronic energy transfer between molecules or ions in solids and in liquids [d]. 4) Enzymatic catalysis [e] 5) Group transfer in biological systems [fl. 6) Electron-hole recombination in semiconductors [g]. 7) Non-radiative electronic relaxation in ionic centers Ih] and in...

The lattice dynamics of molecular crystals has undergone an enor- mous progress in these last twenty years or so. The experimental and theoretical advances have been realized by two different approaches. From one side molecular spectroscopists have been primarily interested in the vibrational properties of the molecules themselves subjected to the perturbing influence of the crystal environment. From the other side the lattice dynamical theory familiar in solid state physics for atomic lattices has been extended to molecular arrays. Although the overlap between the two approaches has been...

In the last fifty years. computational chemistry has made impressive strides. Huckel NO computations were rapidly succeeded by semiempirical monodeterminantal Self Consistent Field (SCF) MO calculations which now give way to high quality ab initio calculations of the poly-determinantal SCF-MO and Generalized VB variety. By contrast. no analogous progress has been made in the area of the qualitative theo~ of chemical bonding. In fact. more than a half-centu~ after the exposition of HUckel MO theory the conceptual superstructure of chemist~ is still founded on it. This is made glaringly evident...