Biirgi, Hans-Beat

As far as model force fields are concerned, it is crucial to build anharmonic components into the molecular mechanics program if you want to have adequate predictive power in the case of crowded molecules. That was borne out strildngly in Hans-Beat Biirgi s study of tri-t-butyl methane where our field turned out to give an excellent representation of the molecule when others, more or less devoid of anharmonic terms, didn t. 

Hans-Beat Biirgi ° has demonstrated that results from a crystal structure determination of metal ion coordination compounds can be interpreted in terms of a variety of intramolecular dynamic processes. Using... 

Most experiments have inherent in them a large number of variables. The experimenter usually ignores most of these variables, assuming on a subjective basis that they are not important. The problem has been stated by Thomas Auf der Heyde and Hans-Beat Biirgi as a twofold one First, how can we avoid subjectively carving up the data into two-dimensional subsets, i.e., how can all n variables be analyzed simultaneously in order to reveal correlations between them Second, how can the dimensionality of the problem be objectively reduced in order to interpret and visualize these correlations Two main methods are presently employed to try to resolve this problem. These methods are cluster analysis, which sorts the data into groups (clusters) so that the data can be classified, and factor analysis, which finds those variables (factors) that account most successfully for the sample variance, that is, the differences or similarities between the various sets of geometric data. 

Hans-Beat Biirgi and Jack D. Dunitz " and their co-workers have postulated that if the mode of restructuring of compounds as a result of a chemical reaction is known, then a study of the detailed geometries of... 

---