Computational chemistry pitfalls

The book is designed for a broad spectrum of users practitioners of computational chemistry who are interested in gaining a broad survey or an entree into a new area of organic chemistry, synthetic and physical organic chemists who might be interested in running some computations of their own and would like to learn of success stories to emulate and pitfalls to avoid, and graduate smdents interested in just what can be accomplished by computational approaches to real chemical problems. 

Finally, most of the published computational studies directed toward chiral chromatography have been carried out by chromatographers rather than by computational chemists. Most of these scientists look at computational chemistry as an adjunct to their experimental work, but understand the information content derived from molecular simulations can provide valuable information not otherwise available. In that sense they are right. However, most chromatographers are not well versed in computational chemistry and make too many serious errors for their results to be of benefit. So, on the one hand there is a need for computational chemistry but on the other hand too many pitfalls exist for the non-expert to step into. The conclusion one draws from this is that chromatographers should work collaboratively with... 

The book is aimed at students and scientists who have a basic understanding of inorganic chemistry. No prior knowledge of theoretical chemistry, sophisticated mathematics, or computing is assumed. The basic concepts of molecular mechanics are developed and discussed in Part I. Examples of applications and the difficulties encountered are reviewed in Part II. In Part III a practical guide to undertaking a molecular modeling study of a new system is presented and the problems and pitfalls likely to be encountered are outlined. The three parts of the book can be read and used separately. 

Because of all of the above pitfalls, NOE is probably the most misinterpreted experiment in organic chemistry. In my experience, /-coupling measurements, both homonuclear and heteronuclear, give far more reliable information than NOE measurements in the determination of small-molecule stereochemistry. To use NOE measurements for stereochemical determinations, it is always best to do the NOESY experiment on both isomers and compare the crosspeak intensities (relative to the diagonal peak intensities) and measure distances on both isomers using an energy-minimized computer model of the structures. If the differences in distance and NOE intensity are small between the two isomers, the experiment cannot be conclusive. 

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