Koch-Popelier criteria

The 90 K X-X study on coumarin and its derivatives [87] (column 1 in Table 3) stretches the limit of what local BCP indices can tell us about these weak interactions. The combined analysis of 36 contacts (15 C-H- -O and 21 C-H- - -tt), all satisfying the Koch-Popelier criteria, reveals a narrow range of H- - -A distances (2.75-2.85 A) what is believed to correspond to an overlap between the two types of interactions. This observation is fully supported by periodic B3LYP/6-31G calculations, since the local indices derived by the two methods are in fair agreement. However, the charge depletion at the... 

The above argument stresses the importance of adapting the Koch-Popelier criteria [40] in experimental studies, since they include not only local but also integrated topological properties to characterize HBs. New density-based... 

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