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Generalized Hirshfeld Partitioning with Oriented and Promoted Proatoms

物理化学学报 2018年第5期34卷 514-518页

作者： heidar-zadeh farnaz AYERS Paul W. Department of Chemistry & Chemical Biology McMaster University Hamilton Ontario L8P 4Z2 Canada Department of Inorganic and Physical Chemistry Ghent University Krijgslaan 281 (S3) 9000 Gent Belgium Center for Molecular Modeling Ghent Uni

In this study, we show how to generalize Hirshfeld partitioning methods to possibly include non-spherical proatom densities. While this generalization is numerically challenging(requiring global optimization of a large number of parameters), it is conceptually appealing because it allows the proatoms to be pre-polarized, or even promoted, to a state that more closely resembles the atom in a molecule. This method is based on first characterizing the convex set of proatom densities associated with the degenerate ground states of isolated atoms and atomic ions. The preferred orientation of the proatoms' densities are then obtained by minimizing the information–theoretic distance between the promolecular and molecular densities. If contributions from excited states(and not just degenerate ground states) are included in the convex set, this method can describe promoted atoms. While the procedure is intractable in general, if one includes only atomic states that have differing electron-numbers and/or spins, the variational principle becomes a simple convex optimization with a single unique solution.

关键词：分子量分子密度激发态原子状态

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Quantitative Electrophilicity Measures

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物理化学学报 2018年第6期34卷 662-674页

作者： GONZáLEZ Marco Martínez CáRDENAS Carlos RODRíGUEZ Juan I. LIU Shubin heidar-zadeh farnaz MIRANDA-QUINTANA Ramón Alain AYERS Paul W. Laboratory of Computational and Theoretical Chemistry Faculty of Chemistry University of Havana Havana 10400 Cuba. Departamento de Quimica and Centro de Quimica Universidade de Coimbra 3004-535 Coimbra Portugal. Departamento de Fisica Fac

Quantitative correlation of several theoretical electrophilicity measures over different families of organic compounds are examined relative to the experimental values of Mayr et ***,the ability to predict these values accurately will help to elucidate the reactivity and selectivity trends observed in charge-transfer reactions.A crucial advantage of this theoretical approach is that itprovides this information without the need of experiments,which are often demanding and ***,two different types of electrophilicity measures were ***,models derived from conceptual density functional theory(c-DFT),including Parr's original proposal and further generalizations of this index,are *** instance,the approaches of Gázquez et *** Chamorro et *** considered,whereby it is possible to distinguish between processes in which a molecule gains or loses ***,we also explored two novel electrophilicity *** one hand,the potential of environmental perturbations to affect electron incorporation into a system is analyzed in terms of recent developments in *** studies highlight the importance of considering the molecular surroundings when a consistent description of chemical reactivity is *** the other hand,we test a new definition of electrophilicity that is free from inconsistencies(so-called thermodynamic electrophilicity).This approach is based on Parr's pioneering insights,though it corrects issues present in the standard working expression for the calculation of ***,we use machine-learning tools(i.e.,symbolic regression) to identify the models that best fit the experimental *** this way,the best possible description of the electrophilicity values in terms of different electronic structure quantities is ***,this straightforward approach enables one to obtain good correlations between the theoretical and experimental quantities by using the simple,yet p

关键词： Electrophilicity Conceptual density functional theory Symbolic regression Genetic programming Grammatical evolution

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