Virtually NonexistentCorrelation between the OH StretchingFrequency and the Instantaneous Geometry in the Short Hydrogen Bondof Sodium Hydrogen Bis(sulfate): Advanced Chemometrics Analysis.

We examined the correlation between the dynamically sampledanharmonicfrequency of the OH stretching motion and the corresponding instantaneousgeometric parameters associated with the structure of crystallinesodium hydrogen bis(sulfate), which is a benchmark system with anextremely short hydrogen bond. We analyzed the trajectory obtainedby a conventional Car–Parrinello molecular dynamics simulation,followed by an a posteriori quantization of the proton motion. Forstatistical analysis we applied the established methodologies of multiplelinear regression, principal component analysis, principal componentregression, and Kohonen neural networks. No simple correlation schemebetween the OH stretching frequency and any particular geometry parameter(or their combination) was found. In comparison to the establishedcorrelation schemes (e.g., Mikenda and Novak) that consider a series of systems, our study provides a complementary insightinto the nature of hydrogen bonding of a single system, in the sense that it considers the important aspects of fluctuationsof the environment and the resulting broadening of the OH stretchingband, which cannot be adequately assessed by experiment. The absenceof appreciable correlations gives strong evidence of the extreme complexityof short hydrogen bonding. [ABSTRACT FROM AUTHOR]