Design theory affordances

Once we have established the factors responsible for conformational isomerism in 1,3-butadiene, we can attempt to put the insight that theory affords into use by designing dienic systems which will have a maximum chance of existing in a preferred crowded conformation, i. e. a gauche or cis conformation. 

Recent decades have seen the emergence of a novel approach to scientific research, based on the exploitation of fast electronic digital computers. Computation provides a method of investigation which transcends the traditional division between theory and experiment. Computer-assisted simulation and design may afford a solution to complex problems which would otherwise be intractable to theoretical analysis, and may also provide a viable alternative to difficult or costly laboratory experiments. Though stemming from Theoretical Chemistry, Computational Chemistry is a field of research... 

Maier, J. R. Fadel, G. (2001). Affordance The fundamental concept in engineering design. Proceedings of the ASME Design Theory and Methodology Conference. 

In addition, the recent and incredibly fast development of computers, both in architecture and speed, has increased the computing power up to levels that allow the application of quantum theory to fair-sized organic molecules at fairly accurate computational levels (semi-empirical or ab initio with appropriate basis sets) within reasonable time limits and affordable costs. These advances have made possible the development of theoretical molecular descriptors, some of them based on quantum mechanics easier, leading to the concept of Computer-Aided Drug Design. 

Figure 3 illustrates several of the structural innovations that emerged from the discoveries made at LLNL in the first half of 2002. It remains to be seen which of these innovations are best and/or affordably testable in the near term, but all are likely to improve on conventional tanks. Several important holes in current theory and analyses emerged during the recent discovery process. These holes are big enough that several PhD theses may not suffice to fill each one. Fiber number flex conservation, departures from constant (assumed) fiber/matrix ratio, and actual curvilinear (non-axisymmetric, nongeodesic) fiber trajectories will contribute arduous but necessary improvements to current composite design methods. 

An attempt in this direction has, in fact, been made by Preuss >, who recognized the importance of the above problem and developed methods for the treatment of the "incomplete associations of atoms which contain the FIEM (see Section A.) as subsets. The complexity of the Preuss approach limits its application to systems which contain much fewer nuclei and electrons than those involved in complicated chemical problems, such as synthetic design. For the latter, a different type of theory is needed, a theory that affords insights into the relations between complex chemical systems, without the sometimes formidable effort of solving the pertinent quantum mechanical problems. It is, however, conceivable that the potential energy surfaces of polyatomic systems will be the basis of future computer programs for the solution of chemical problems. 

In the molecular sciences it is most appropriate to adopt a pragmatic attitude toward the Dirac equation in order to set up a theory which closely resembles nonrelativistic many-electron theory. We will see that we can afford a number of approximations designed such that the numerical effect on physical observables still resembles that of a truly relativistic many-electron theory. Hence, we proceed from the fundamental physical principles of Einstein s special theory of relativity to approximations of different degree. As a matter of fact this is exactly the program of relativistic quantum chemistry that we shall start to develop in this chapter. 

---