Molecular systems electronic structure

Ames Laboratory (Iowa State University, USA) investigating new solid state phases based on reduced rare earth halides. Since 1993, she has held a position at the University Jaume 1 of Castello (Spain) and became Associate Professor of Physical Chemistry in 1995. During the second semester of 2005, she held a visiting professor position at the Laboratory of Chemistry, Molecular Engineering and Materials of the CNRS-Universtity of Angers (France). Her research has been focussed on the chemistry of transition metal clusters with special interest in multifunctional molecular materials and the relationship between the molecular and electronic structures of these systems with their properties. She is currently coauthor of around 80 research papers on this and related topics. 

Figure 22 DBH ground state equilibrium structure 3 and molecular and electronic structure for the computed low-lying real crossing 10,11. In this system the S1(n-ic )/ S0, T2(n-7ill )/T1(rc-7i 1 ) conical intersections and the T1(Tt-7t ,)/S0 and T2(n-7i,l )/S0 triplet/singlet crossings occur at the same molecular structure. The relevant geometrical parameters are in angstrom units.

Several recent studies examined photoinduced ET in dyads featuring transition metal chromophores that are dissimilar to the d6 transition metal polypyridine complexes used in the type 1 and type 2 dyads that have been discussed in the preceding sections. Since the molecular and electronic structure of the excited states involved in these systems is unique from the type 1 and type 2 dyads, results on these systems are discussed separately. 

Bockstedte M, Kley A, Neugebaur J, Scheffler M (1997) Density-functional theory calculations for poly-atomic systems electronic structure, static and elastic properties and ab initio molecular dynamics, Comput Phys. Commun. 107 187-222... 

In this review the chemistry of some new electron systems, heteroatom-substituted cyclopropenium compounds", is briefly described from the viewpoints of molecular design, synthesis, molecular and electronic structures, and reactions. In each, we have encountered unique problems which will eventually produce novel fruits. In this sense the chemistry of heteroatom-substituted cyclopropenium compounds might indeed furnish topics in current chemistry and also in prospective chemistry. 

The molecular and electronic structures are discussed on the basis of B3LYP and CASPT2 quantum chemical calculations. Paracyclophanes are attractive model compounds for studying specific intramolecular interactions [146, 147]. Gerson et al. [148] showed the radical anion of [2,2] paracyclophane 71 is an unassociated specie, with the unpaired electron being equally distributed over both 7r-systems. 

Density functional techniques are available for the calculation of the molecular and electronic structures of ground state systems. With the functionals available today, these compete with the best ab initio methods. This article focuses on the theoretical aspects associated with the Kohn Sham density functional procedure. While there is much room for improvement, the Kohn-Sham exchange-correlation functional offers a great opportunity for theoretical development without returning to the uniform electron gas approximation. Theoretical work in those areas will contribute significantly to the development of new, highly precise density functional methods. 

Density functional techniques are available for the calculation of the molecular and electronic structures of ground state systems. Techniques of this kind are also applied extensively in the study of classical liquids, where applications cover a broad spectrum ranging from fluids at interfaces to theories of freezing and nucleation. The area of nuclear physics is still in a very early stage of development in the use of DFT, mainly because there is not yet a complete theory, as there is in the molecular and atomic cases. This chapter has focused on the theoretical aspects of other applications not related to the use of the Kohn-Sham procedure for electronic systems, with the hope that a better understanding of the problems and successes in the respective areas would help in the development of improved functionals. 

The compositional and structural diversity of polyoxometalates, coupled with their remarkable catalytic, magnetic, medicinal, redox, and photophysical properties, justifies their description as class of inorganic compounds "unmatched in terms of molecular and electronic structural versatility, reactivity and relevance". The development of rational methods for the systematic modification and functionalization of polyoxometalates is a challenging endeavor, hut is one which offers the prospect of exploiting more fully the desirable attributes of these systems. 

M. Bockstedte, A. Kley, J. Neugebauer, and M. Scheffler, Comput. Phys. Commun., 107,187 (1997). Density-Functional Theory Calculations for Polyatomic Systems Electronic Structure, Static and Elastic Properties and Ab Initio Molecular Dynamics. 

The central mechanistic feature in most photochemical mechanisms is the conical intersection. Thus we hope to present some thoughts about how to predict and rationalize the molecular and electronic structure of such mechanistic features using VB ideas. It turns out that one can derive analytical results for n orbitals with n electrons so we shall develop the main ideas with reference to the photochemistry of some simple model systems such as the cycloaddition of two ethylene molecules and the radiationless decay of benzene. Once one allows zwitterionic systems, lone pairs and heteroatoms, the same principles apply but analytical results are not available so easily and one must be content with a qualitative analysis at the moment. 

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