Molecular Inventor system

A notable hybrid between representation by geometrical objects and structure data is the Molecular Inventor (MI) system from Silicon Graphics. MI is based on the standard Inventor file format, which is very similar to VRML 1,0, In addition to normal Inventor nodes, a MI file contains additional nodes which describe a chemical structure and attached physicochemical data. Because both arbitrary visualizations and structure-oriented data for potential extraction and further processing are stored together in one file, the best features from both approaches are combined. The major problem is portability MI viewers are available for free, only for Silicon Graphics platforms. Commercial versions for PCs can now be purchased. Compared to the much easier and generally free availability of viewers both for pure VRML and for chemical MIME data, this severely reduces the general acceptance of this product. 

Poly(vinyl dnnamate) is the earliest synthetic photo-polymer Its molecular structure, the polyvinyl backbone with dnnamoyl side drains, was proposed with the expectation that the photocycloaddition of polymer-bound dnnamoyl groups would crosslink adjacent macromolecules. The practical aims of the inventors were realized, and the whole range of successful photopolymos has been developed from the ordinal idea However, the actual mechanism of oosslink formation in these systems remained unclarified untD recently. Repeated attonpts to identify cyclobutane derivatives in irradiated films of poly(vinyl dimamate) failed with traces of a-truxiUic acid detected in the hydrolyzed material only at the very early stage of irradiation. Schmidt... 

The functional Eex(R) is the key to the whole business the exchange-correlation energy. Whether E does contain appropriate electron correlation contributions depends on whether SexiR) is indeed a realistic energy density. A first crude approximation, whose partial success was a surprise even to its inventors, is to use the exchange-correlation energy of an electron gas of uniform density, equal to the local density in the molecular system at point R (the local density approximation, LDA). Other more sophisticated approaches have been proposed, hence the various names appended to a DFT calculation (B, BP, B-LYP, and the like). The technical details for these formulations [15,16] are beyond the scope of this book. 

---