Towards a realistic model for the quantitative evaluation of intermolecular potentials and for the rationalization of organic crystal structures. Part I. Philosophy†
Calculations on prototypical dimer structures and representative crystal structures of organic compounds have been carried out by SCDS-Pixel, a new method for the evaluation of intermolecular potentials. Systems not included in the set originally employed in calibration of the method are considered, and a significant improvement in performance is obtained by adjustment of the disposable parameters over a wider collection of experimental and computational evidence. The results cast some new light on the organization of molecular crystals, and suggest that the density sums method is an advantageous alternative to atom–atom potential techniques, as concerns both detailed quantitative results and general ways of thinking about crystal packing. While the SCDS-Pixel method, as it is now, is general and applicable to a wide range of chemical systems, further development and improvements are possible and a few sensitive points in this respect are examined.