On Computational Support for Theoretical

So despite the failure of the 1970 Conference on Computational Support for Theoretical Chemistry to achieve its aims, computational chemistry flourished during the 1980s. Evidence of this can be found in the appearance of new journals and in the expansion of the literature. A long list of journals and newsletters dedicated to computer-aided chemistry, along with their dates of inception, has been presented by Kenneth Lipkowitz and Donald Boyd, computational chemists and editors of Reviews in Computational Chemistry (see Table 1). Lipkowitz and Boyd also presented data on the number of articles abstracted by the Chemical Abstracts Service from 11 journals covering aspects of computational chemistry. Their data showed a general increase in the number of articles, with some fluctuations, going from approximately 680 in 1978 to approximately 1175 in 1988. ... 

Chemists use computers for many purposes. As the previous sections on instrumental methods have illustrated, every modem analytical instrument must include a computer interface. Chemical structure drawing, visualization, and modeling programs are important computer-supported applications required in academic, industrial, and governmental educational and research enterprises. Computational chemistry has allowed practicing chemists to predict molecular structures of known and theoretical compounds and to design and test new compounds on computers rather than at the laboratory bench. 

In 1966, the DFG decided to initiate a special priority program for theoretical chemistry for the next 5 years in order to support this field on a broad basis.The intention was to support primarily new ideas and the development of methods in theoretical chemistry and to a lesser extent computations. 

Then the computations on the 2,5-cyclohexadienones were used to obtain 3, 3-bond orders of the five electronic states listed in Scheme 1.5. As noted above, such bond orders between nonconjugated centers are equivalent to a perturbation computation and provide information on tendencies of the two centers to bond. There are positive bond orders for three of these states. However, it is known that the Type A rearrangement occurs selectively from a triplet, and only the n-x triplet has a positive bond order, thus providing theoretical support for the reaction mechanism. 

Extensive computational studies have been carried out on the )8-(acyloxy)alkyl and ff-( phosphatoxy)alkyl rearrangements by Radom and coworkers and by Zipse. These calculations in general support the possibility of concerted rearrangements taking place via 5-center-5-electron and 3-center-3-electron cyclic transition states [25, 26]. However, before such computations can be used as an aid in distinguishing between reaction pathways, it will be necessary for theoretical chemists to circumvent the present difficulties in calculating the radical ionic fragmentations. 

At the second level is the use of the computer in a laboratory-like setting to accompany and support the quantum chemistry lectures. In the 1970s an effort was begun to develop a series of computer exercises that could serve as the laboratory component for theoretical chemistry. Students find quantum chemistry to be an abstract, highly mathematical subject, and unless its concepts are translated into action in some way it is unlikely that they will master its principles or discover its applications in other disciplines. Hands on in quantum chemistry means hands on the keyboard of a computer. Therefore, the goal was to create a repertoire of computer exercises that juxtaposes the theoretical framework of quantum chemistry and its computational methodology. 

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