Hierarchies of Intermolecular Potentials and Forces: Progress Towards a Quantitative Evaluation

Abstract

Conventional views of intermolecular cohesion, based on the traditional categories of hydrogen bonding, of aromatic interactions, of dipolar or quadrupolar contacts, and of the broad, gray zone of 'van der Waals' liaison, often define strength hierarchies on the basis of qualitative categories like approximate molecular orientations or distances between atomic nuclei in molecules. When interaction energies are quantitatively evaluated between molecular pairs, in a more justifiable partitioning scheme, often a completely different picture emerges. Examples are given for selected molecular dimers and organic crystals, using a new semiempirical scheme, the PIXEL method, which also allows a separate evaluation of coulombic, polarization, dispersion and repulsion energy terms.

The effect of pressure on the crystal structure of bianthrone

“…H-atom distances were set to standard neutron values in all calculations (C-H = 1.083 Å ). The electron density was used to evaluate packing energies using the PIXEL method as implemented in the program OPiX (Gavezzotti, 2003). The output from these calculations yields a total packing energy and a breakdown into component interactions.…”

“…The output from these calculations yields a total packing energy and a breakdown into component interactions. Each energy is further broken down into its Coulombic (electrostatic), polarization, dispersion and repulsion contributions (Gavezzotti, 2005(Gavezzotti, , 2007.…”

High-pressure polymorphism in L-serine monohydrate: identification of driving forces in high pressure phase transitions and possible implications for pressure-induced protein denaturation

“…The development of the PIXEL method [36][37][38][39] for the calculation of intermolecular packing energies, has enabled this simple model for the driving forces of phase transitions to be tested. It has been found to be valid in the phase transition from salicylaldoxime-I to II: as the pressure approached 5.9 GPa a hydrogen-bonded pseudo-macrocyclic dimer became rapidly less stable, and a rearrangement of the hydrogen bonds ensued.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 16, 2005) and the discipline

“…Gavezzotti [73] in the first article presents the PIXEL method, which allows a separate evaluation of coulombic, polarization, dispersion, and repulsion energy terms and makes a progress toward a quantitative evaluation of intermolecular potentials and forces including hydrogen bonding. Examples are given for selected molecular dimers and organic crystals.…”