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(Created page with '<<< Topological Approaches to Intermolecular Interactions workshop main page === Context and motivation === Valence Bo…')
 
 
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[[Topological_Approaches_to_Intermolecular_Interactions|<<< Topological Approaches to Intermolecular Interactions workshop main page]]
 
[[Topological_Approaches_to_Intermolecular_Interactions|<<< Topological Approaches to Intermolecular Interactions workshop main page]]
  
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=== Context and motivation ===
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=== Introduction ===
  
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Valence Bond (VB) theory provides an unmatched intimate connection between the accurate quantum theory and chemical concepts - models which chemists use for ‘thinking’ about chemistry (localized electron pairs, Lewis model, resonance and hybridization...), and thus is a novel method for the simulation of molecules compared with the much popular Molecular Orbital (MO) Theory.  
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Revealing the chemical bonding (structure) and the reorganization of the chemical bonds (reactivity) of any molecular system forms the undisputed foundation of chemistry. Chemical interactions between a protein and a drug, or a catalyst and its substrate, self-assembly of nanomaterials, and also many chemical reactions are dominated by noncovalent interactions. This class of interactions spans a wide range of binding energies and encompasses hydrogen bonding, dipole−dipole interactions, steric repulsion, and London dispersion. Molecular structure is governed by covalent, noncovalent, and electrostatic interactions, the latter two of which are the driving force in most biochemical processes.
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The three-dimensional molecular structure defines covalent bonds; however, noncovalent interactions are hidden within voids in the bonding network. Although there are several ways to view and analyze covalent and electrostatic interactions, analogously simple methods for noncovalent interactions are rare. The development of such methods aids understanding of the complex interactions between biomolecules and the design of self-assembled materials and drugs, among others.
  
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Despite its unique interpretative capabilities, VB theory and its various implemented methods are still used by a still limited community of chemists. Moreover, this beautiful theory is barely taught anymore in advanced university courses. This is because starting from the 1970s, accurate and efficient electronic structure methods that could be implemented were largely based on MO Theory, which utilizes orthogonal orbitals. These methods have been continuously improved and very intensively used to solve many problems in chemistry, physics and biology. At the same time, the development of accurate ab initio VB methods has been significantly impeded by algorithmic difficulties, mostly related to the non-orthogonal problem at the roots of VB theory.
 
  
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=== Purposes ===
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One such proposal is the noncovalent interaction (NCI) index. It enables visualization and quantification of noncovalent theoretical results. NCI enables identification of interactions in 3D space from the electron density. Moreover, this approach has the advantage of being transferable to large systems, while remaining very fast to compute. Consequently, a qualitative NCI analysis is applicable to extremely large systems, including, e.g. proteins and DNA, where describing the interplay of attractive and repulsive interactions is crucial for understanding functionality. This new index, requiring only molecular geometry information, compliments existing methods for covalent and electrostatic interactions, providing a perfect bridge between theoretical chemistry and (in)organic chemistry by means of chemical bonds and their change.
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Following these motivations, the purposes of this workshop will be three-fold :
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* to be a meeting ground for chemists from diverse scientific communities, whose interest are related with aspects of ab initio VB theory,
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* to stimulate further developments in VB methods and algorithms, new applications of VB theory to chemical problems, and new collaborations,
 
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* to guide newcomers to ab initio Valence Bond to learn the necessary basics of the theory and start using some of the available VB codes
 
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=== Overview ===
 
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Considering its purposes, the workshop will contains :
 
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* plenary lectures on Valence Bond theory, methods, and related models,
 
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* extension lectures to provide connections between VB and other related wave function and interpretative methods
 
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* short talks given by participants on a topic relevant to VB theory
 
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* ample space dedicated to free discussions
 

Dernière version du 9 janvier 2013 à 10:22

<<< Topological Approaches to Intermolecular Interactions workshop main page

Introduction

Revealing the chemical bonding (structure) and the reorganization of the chemical bonds (reactivity) of any molecular system forms the undisputed foundation of chemistry. Chemical interactions between a protein and a drug, or a catalyst and its substrate, self-assembly of nanomaterials, and also many chemical reactions are dominated by noncovalent interactions. This class of interactions spans a wide range of binding energies and encompasses hydrogen bonding, dipole−dipole interactions, steric repulsion, and London dispersion. Molecular structure is governed by covalent, noncovalent, and electrostatic interactions, the latter two of which are the driving force in most biochemical processes.

The three-dimensional molecular structure defines covalent bonds; however, noncovalent interactions are hidden within voids in the bonding network. Although there are several ways to view and analyze covalent and electrostatic interactions, analogously simple methods for noncovalent interactions are rare. The development of such methods aids understanding of the complex interactions between biomolecules and the design of self-assembled materials and drugs, among others.


One such proposal is the noncovalent interaction (NCI) index. It enables visualization and quantification of noncovalent theoretical results. NCI enables identification of interactions in 3D space from the electron density. Moreover, this approach has the advantage of being transferable to large systems, while remaining very fast to compute. Consequently, a qualitative NCI analysis is applicable to extremely large systems, including, e.g. proteins and DNA, where describing the interplay of attractive and repulsive interactions is crucial for understanding functionality. This new index, requiring only molecular geometry information, compliments existing methods for covalent and electrostatic interactions, providing a perfect bridge between theoretical chemistry and (in)organic chemistry by means of chemical bonds and their change.

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