Quantitative structure-property quantum chemical method

PW91 (Perdew, Wang 1991) a gradient corrected DFT method QCI (quadratic conhguration interaction) a correlated ah initio method QMC (quantum Monte Carlo) an explicitly correlated ah initio method QM/MM a technique in which orbital-based calculations and molecular mechanics calculations are combined into one calculation QSAR (quantitative structure-activity relationship) a technique for computing chemical properties, particularly as applied to biological activity QSPR (quantitative structure-property relationship) a technique for computing chemical properties... 

The aforementioned macroscopic physical constants of solvents have usually been determined experimentally. However, various attempts have been made to calculate bulk properties of Hquids from pure theory. By means of quantum chemical methods, it is possible to calculate some thermodynamic properties e.g. molar heat capacities and viscosities) of simple molecular Hquids without specific solvent/solvent interactions [207]. A quantitative structure-property relationship treatment of normal boiling points, using the so-called CODESS A technique i.e. comprehensive descriptors for structural and statistical analysis), leads to a four-parameter equation with physically significant molecular descriptors, allowing rather accurate predictions of the normal boiling points of structurally diverse organic liquids [208]. Based solely on the molecular structure of solvent molecules, a non-empirical solvent polarity index, called the first-order valence molecular connectivity index, has been proposed [137]. These purely calculated solvent polarity parameters correlate fairly well with some corresponding physical properties of the solvents [137]. 

The concept of bond polarity, which is used in main group chemistry with reference to electronegativities of the atoms involved, is less readily applied in a quantitative way to bonds between transition metals. Their nature may be more significantly influenced by the coordination spheres of the metal centers involved rather than intrinsic properties of the metal itself. This increased level of sophistication required in a meaningful discussion of bond polarity in M-M bonds necessitates elaborate quantum chemical methods to be used. However, this may render it difficult to extract information from the results of such calculations, which are interpretable within the established paradigms of structure and bonding familiar to the chemist. 

Taking into account the paucity of quantitative data on insect repellents and the objectives discussed earlier, repellent structure and electronic properties were initially investigated using quantum chemical methods to determine any functional dependence on protection time as measured... 

In principle, quantum-chemical theory should be able to provide precise quantitative descriptions of molecular structures and their chemical properties however, due to mathematical and computational complexities this seems unlikely to be realized in the foreseeable future. Thus, researchers need to rely on approximate methods that have now become routine and have found wide applications. In many cases, errors due to the approximate nature of quantum-chemical calculations and the neglect of the solvation effects are largely transferable within structurally related series (Karelson and Lobanov, 1996). Thus, relative values of calculated descriptors can be meaningful even though their absolute values are not directly applicable. 

The proposed volume provides basic information as well as the details of computational and computational-experimental studies improving our knowledge on functioning of alive, different properties of drugs, and predictions of new medicines. Whenever it is possible the interplay between the theory and the experiment is provided. The unique feature of the book is the fact that such different in principles computational techniques as quantum-chemical and molecular dynamic approaches on one hand and quantitative structure-activity relationships on another hand are considered inside one volume. The reviews presented in the volume cover main tendencies and priorities in apphcation of computational methods of quantum chemistry, molecular dynamics and chemoinformatics to solve the tasks of pharmacy and medicine. 

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