Bader theory

Schowen (1972) used the Swain-Bader theory to explain solvent kinetic isotope effects on SN2 reactions involving halides, in terms of the numer of water molecules solvating a halide ion in the transition state (assumed to be three) vs. the number solvating it in the bulk (four). The contribution of a single halide-water hydrogen bond was also taken to depend on the partial charge on the halide, which could be consistent with either theory. 

R.F.W. Bader Theory of Molecular Structure Studies Phys. Theor. Chem. 28 (1983) 40. 

In a recent study on the intramolecular dihydrogen bridges of 2-cyclopropyl ethanol derivatives [64] (for the molecular scheme see Fig. 3), calculations predicted that the open conformations are more stable than the closed ones and the observed interactions are probably only H- -H van der Waals contacts although the analysis of the parameters derived from the Bader theory shows that such O-H- - -H-C contacts may be classified as H-bonds . More convincing is the... 

In this volume mainly the theoretical studies are presented, however also examples of experimental results are included and all the computational results are strongly related to experimental techniques. The most important topics considered in the recent studies on hydrogen bond are discussed in this volume, such problems as how to estimate the energy of intramolecular H-bonds, covalency of these interactions, the distant consequences of H-bond since in earlier studies usually only the X-H- Y H-bridge was analyzed (X-H is the proton-donating bond and Y is an acceptor), the differences between H-bond and van der Waals interactions from one side and covalent bonds from the other side, the use of the Bader theory to analyze different kinds of H-bonds, the influence of weak H-bonds upon structure and function of biological molecules, etc. There are also topics related to the experimental results crystal structures, infrared and NMR techniques and many others. 

R. F. W. Bader, Theory of Atoms in Molecules , Department of Chemistiy, McMaster University, Canada, 1995 http //www.chemistry.mcmaster.ca/faculty/bader/aini/... 

R F W Bader s theory of atoms in molecules [Bader 1985] provides an alternative way to partition the electrons between the atoms in a molecule. Bader s theory has been applied to many different problems, but for the purposes of our present discussion we will concentrate on its use in partitioning electron density. The Bader approach is based upon the concept of a gradient vector path, which is a cuiwe around the molecule such that it is always perpendicular to the electron density contours. A set of gradient paths is drawn in Figure 2.14 for formamide. As can be seen, some of the gradient paths terminate at the atomic nuclei. Other gradient paths are attracted to points (called critical points) that are... 

The theory of atoms in molecules of R. F. W. Bader and coworkers provides another, more sophisticated approach to atomic charges and related properties. Jerzy CiosJowski has drawn on and extended this theory, and he is responsible for the AIM faciJityin Gaussian. 

In Chapter 3, we studied the topic of population analysis. In population analysis, we attempt a rough-and-ready numerical division of the electron density into atom and bond regions. In Mulliken theory, the bond contributions are divided up equally between the contributing atoms, giving the net charges. The aim of the present section is to answer the questions Are there atoms in Molecules , and if so, How can they be defined . According to Bader and coworkers (Bader, 1990) the answers to both questions are affirmative, and the boundaries of these atoms are determined by a particular property of the electron density. 

Bader, R. F. W. (1990) Atoms in Molecules. A Quantum Theory, Clarendon Press, Oxford. Baker, J. (1986) J. Comput. Chem. 7, 385. 

Bader RFW (1994) Atoms in molecules a quantum theory. Oxford University Press, New York... 

Bader, R.F.W. (1991) Atoms in Molecules. A Quantum Theory. Oxford University Press. 

In this paper a method [11], which allows for an a priori BSSE removal at the SCF level, is for the first time applied to interaction densities studies. This computational protocol which has been called SCF-MI (Self-Consistent Field for Molecular Interactions) to highlight its relationship to the standard Roothaan equations and its special usefulness in the evaluation of molecular interactions, has recently been successfully used [11-13] for evaluating Eint in a number of intermolecular complexes. Comparison of standard SCF interaction densities with those obtained from the SCF-MI approach should shed light on the effects of BSSE removal. Such effects may then be compared with those deriving from the introduction of Coulomb correlation corrections. To this aim, we adopt a variational perturbative valence bond (VB) approach that uses orbitals derived from the SCF-MI step and thus maintains a BSSE-free picture. Finally, no bias should be introduced in our study by the particular approach chosen to analyze the observed charge density rearrangements. Therefore, not a model but a theory which is firmly rooted in Quantum Mechanics, applied directly to the electron density p and giving quantitative answers, is to be adopted. Bader s Quantum Theory of Atoms in Molecules (QTAM) [14, 15] meets nicely all these requirements. Such a theory has also been recently applied to molecular crystals as a valid tool to rationalize and quantitatively detect crystal field effects on the molecular densities [16-18]. 

Bader et al. have developed a theory of molecular structure [8], based on the topological properties of the electron density p(r). In this theory, a molecule may be partitioned into atoms or fragments by using zero-flux surfaces that satisfy the condition... 

So far we have considered the shape of the electron density of a limited inner region of each atom but not of the complete atom. How do we find the shape of the complete atom In other words, how do we find the interatomic surfaces that separate one atom from another and define the size and shape of each atom The atoms in molecules (AIM) theory developed by Bader and coworkers (4) provides a method for doing this. 

Bader, R F. W. Atoms in Molecules A Quantum Theory Oxford University Press Oxford, 1990. 

Bader, R. F. W., and T. T. Nguyen-Dang. 1981. Quantum Theory of Atoms in Molecules-Dalton Revisited. Adv. Quant. Chem. 14, 63. 

The final part is devoted to a survey of molecular properties of special interest to the medicinal chemist. The Theory of Atoms in Molecules by R. F.W. Bader et al., presented in Chapter 7, enables the quantitative use of chemical concepts, for example those of the functional group in organic chemistry or molecular similarity in medicinal chemistry, for prediction and understanding of chemical processes. This contribution also discusses possible applications of the theory to QSAR. Another important property that can be derived by use of QC calculations is the molecular electrostatic potential. J.S. Murray and P. Politzer describe the use of this property for description of noncovalent interactions between ligand and receptor, and the design of new compounds with specific features (Chapter 8). In Chapter 9, H.D. and M. Holtje describe the use of QC methods to parameterize force-field parameters, and applications to a pharmacophore search of enzyme inhibitors. The authors also show the use of QC methods for investigation of charge-transfer complexes. 

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