Molecular structure programs fragments

Rather than a single program, DENDRAL was a group of interrelated programs that took turns to participate in a discussion with the user, proposing possible molecular structures for the user to consider and removing from consideration any structure that the user deemed not to be chemically stable, incompatible with the observed fragmentation pattern, or otherwise... 

Graphical pre- and postprocessor for semiempirical molecular orbital programs extended Hiickel, MOPAC, and ZINDO. Structure building from library of fragments and molecules manipulation. Stick, ball-and-stick, and space-filling display. Orbital, electron density, and electrostatic maps. Reaction energy surfaces. IR and UV spectra. MM2 energy minimization. Dynamics. 

Unit cell dimensions were obtained after the indexing of the patterns using the programs of Wemer, Visser, and Shirley.The space group was then determined by consideration of the systematic extinction conditions. The lattice parameters and packing coefficients were consistent with two molecules in the unit cell (see Table 5.13). An initial model for the molecular structure was built for 6,13-dichloro-triphendioxazine using standard fragments. An initial optimization of this structure... 

The program system COBRA [118, 119] can be regarded as a rule- and data-based approach, but also applies the principles of fragment-based (or template-based) methods extensively (for a detailed description sec Chapter 11, Sections 7.1 and 7.2 in the Handbook). COBRA uses a library of predefined, optimized 3D molecular fragments which have been derived from crystal structures and foi ce-field calculations. Each fi agment contains some additional information on... 

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