Spin-polarized Conceptual Density Functional theory: Application to Radicalar and Phototchemical Reactions.

Project Details

Description

Aim: During the last fiteen years, the importance of "density functional theory" (1-7) in quantum chemistry has increased dramatically. This theory, based on the Hohenberg-Kohn theorems (6), uses the electron density p(r) as the basis of all the information of an atomic or molecular system insteead of the wave function Y. Moreover, a variational principle can be formuled wich results practically in the Kohn-Sham orbital equations (7), in wich the only unknown is the socalled exchange-correlation functional Exc is (7), containing next to a kinetic energy part also the non-classical part of the electron-electron repulsion. The search for accurate approximations for this funcitonal is one of the basic themes of research in this area: accurate forms of this functional permit the calculation of many atomic and molecular properites with a comparable quality as the more traditional ab initio correlated methods but with a more much favourable computational cast (1-7). This area of comtemporary DFT research was termed as "Computational DFT" by Professor R.G. Parr, one of the leading authorities in the field (3,4). The search for fast and computationally efficient DFT based algorithms can also be classified under this name. Next to the calculational aspect of DFT, there is also "conceptual" DFT, based on the fact that the response of the system to perturbations in variables such as its number of electrons or external potential (i.e. the potential due to the nuclei) will yield chemically interesting information about the system (3,4,8,9). In the past, this has allowed to identify interesting concepts, commonly used by chemists but often vaguely defined, with these response functions. In this way, these quantities received a sharp theoretical definition, allowing their first principles calculation. Examples of these properties are e.g. the electrnegativity (10,11), hardness (12-14) and softness (12,13,15) and the frontier molecular orbital reactivity indices of Fukui (16,17). In addition, certain principles, such as Sanderson's principle of electronegativity aqualization (18) and Pearson's hard and soft acids and bases (12,13,19) and maximum hardness principles (12,13,20), received theoretical justification.(21)
In this research project we wish, using the concepts and computational methods of Density Functional Theory, to gain deeper insight into the properties and the reactivity of molecules in their excited state (photochemistry) and radicals, or, more generally, in molecules with a different electron density of the & and the B electrons (spin-polarized) systems (22-24). It thus constitutes a logical and new extension of the different studies conducted in our research group in the past to the study of the properties, reactivity and rgioselectivity between interacting spin-polarized systems.

Objectives: The research proposal aims at providing a solid basis for the use of conceptual DFT in the study of the properties ans the reactivity of spin-polarized systems and canbe divided into two main parts.
AcronymFWOAL380
StatusFinished
Effective start/end date1/01/0631/12/09

Keywords

  • chemistry

Flemish discipline codes

  • Biological sciences