Goals and Future Outlook

Finally, soHd-state physicists make use of molecular crystals when they wish to understand certain aspects of soUd-state physics better theoretically and experimentally. Weak intermolecular bonding forces, electrical conductivity with a very narrow handwidth, large anisotropies in their electrical, optical and magnetic properties, one-dimensional conductivity. Unear excitons, and linear magnetic ordering states are best studied in these material classes. 

Such specific properties are the reason why the organic molecular crystals and soUds assume a special status within the wide field of the chemistry and physics of solid materials. We will thus make an effort to show which new concepts in solid-state physics are necessary or helpful for the understanding of these materials. 

Note the problems for Chap. 1 involve the fundamentals of chemical bonding, electron transfer, electron and energy exchange and the Hiickel model of the linear combination of the 2pz atomic orbitals of the C atoms to yield the n orbitals of aromatic molecules (LCAO-MO). Knowledge of these fundamentals of molecular physics is a precondition for using this book. Solutions to the following problems 1—4 can be found in the corresponding chapters of textbooks on molecular physics. 

Problem 1.1. Chemical Bonding 1 the hydrogen molecular ion, HJ, electron and charge transfer  

The model system HJ is the simplest for chemical bonding and for electron transfer. HJ consists of two protons a and b at a distance R, with one electron. (See e.g. Hermann Haken and Hans Christoph Wolf, Molecular Physics and Elements of Quantum Chemistry, 2nd ed.. Springer-Verlag (2004), Sect 4.3, page 58 ff.) 

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