Electronic structure future trends

Iolymers play an increasingly important role in the construction of integrated circuitry (IC) and electronic devices. Future trends in electronics include continuing efforts toward further miniaturization and the manufacture of ever more complex structures. These trends require exceptional materials that are relatively easy to process. Polymers do have an advantage over ceramics and other inorganic materials because of easier processing conditions. 

Some aspects of computational quantum chemistry applied to the analysis of the electronic structure of polymers are reviewed in connection with the timely trends observed in their electrical and optical properties. The paper is organized as follows after an introduction (Section 36.1), the basic theory of the quantum chemical methodologies as applied to periodic chains is summarized (Section 36.2). Several fields of applications are then presented photoelectron spectra (Section 36.3), conducting and semiconducting conjugated polymers (Section 36.4), hnear and non-linear optical properties (Section 36.5) and the role of charge transfer in organic chains (Section 36.6). Possible developments for the near future are also sketched. 

With the improvement in hardware and software tools, the ab initio electronic structure calculations will gain importance because they can deal with increasingly complex systems and yield higher precision in the result. Along with this trend, the hybrid techniques will grow in relevance. It is expected that the hybrid methods will play an important role in the molecular-level modelling of SOFCs in the near future. 

It should be clear from the preceding examples that theoretical studies of this type serve not simply to validate computational predictions by detecting potential sources of error, but also to identify the origins of particular spectroscopic characteristics, establish trends, and uncover correlations between structural or electronic features and spectroscopic observables. It remains to be seen in future applications how far this approach can take us in establishing reliable connections between structural parameters and spectroscopic properties for larger and more complex oligonuclear transition metal systems. 

Recent trends in x-ray diffraction are the increased use of electronic data collection and computer analysis, and in situ or dynamic experiments. These include experiments where the x-ray patterns are obtained while the sample is stretched, heated to its melting point, or aligned with an electric field. Synchrotron radiation is several orders of magnitude more intense than regular laboratory x-ray sources, and its use allows real-time study of deformation or fiber spinning, for example. More synchrotron sources usable for polymer science are currently being built, and although they are limited to national facilities, access should improve in the future. The increased power of computer data analysis permits whole pattern analysis where the crystal structure, orientation and crystallinity are simultaneously determined [10]. More detailed numerical analysis has led to interpretation of x-ray patterns in terms of three phases in semicrystalline polymers instead of the usual two. 

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