Dispersion Interactions between Molecules in and out of Equilibrium Geometry: Visualization and Analysis

Abstract

The London dispersion interactions between systems undergoing bond breaking, twisting, or compression are not well studied due to the scarcity and the high computational cost of methods being able to describe both the dynamic correlation and the multireference character of the system. Recently developed methods based on the Generalized Valence Bond wave function, such as EERPA-GVB and SAPT(GVB) (SAPT = symmetry-adapted perturbation theory), allow one to accurately compute and analyze noncovalent interactions between multireference systems. Here, we augment this analysis by introducing a local indicator for dispersion interactions inspired by Mata and Wuttke’s Dispersion Interaction Density [ 27761924 J. Comput. Chem. 2017 38 15 23 ] applied on top of an EERPA-GVB computation. Using a few model systems, we show what insights into the nature and evolution of the dispersion interaction during bond breaking and twisting such an approach is able to offer. The new indicator can be used at a minimal cost additional to an EERPA-GVB computation and can be complemented by an energy decomposition employing the SAPT(GVB) method. We explain the physics behind the initial increase, followed by a decrease in the interaction of linear molecules upon bond stretching. Namely, the elongation of covalent bonds leads to the enhancement of attractive dispersion interactions. For even larger bond lengths, this effect is canceled by the increase of the repulsive exchange forces resulting in a suppression of the interaction and finally leading to repulsion between monomers.

Raman Evidence of Multiple Adsorption Sites and Structural Transformation in ZIF-4

“…This result strongly suggests the interaction of the C–H centers with the gas molecules. Since the predominant interactions are dispersion interactions owing to the inert nature of the gases, the C–H and π cloud can be the only interacting sites . However, any twist or change in the π center would have resulted in elongation/compression of bonds causing a peak shift or broadening in the mode which we did not observe.…”

“…Since the predominant interactions are dispersion interactions owing to the inert nature of the gases, the C−H and π cloud can be the only interacting sites. 33 However, any twist or change in the π center would have resulted in elongation/compression of bonds 33 causing a peak shift or broadening in the mode which we did not observe. Here, a change in the spectral profile of C−H modes occurs suggesting the varying environment around the C−H centers due to their proximity to the guest molecules.…”

Geminal-based electronic structure methods in quantum chemistry. Toward a geminal model chemistry

“…134,135 Additional insights into the nature of dispersion interactions can be provided by local indicators. 138…”

“…For this purpose, a qualitative analysis is required where the complex information encoded in the electronic wave function is elucidated. Possible tools are molecular properties like dipole moments, 8,11 (natural) occupation numbers, 11,57 local spins, 49 indicators, 138 and various correlators. 11,66,105,[170][171][172][173][174][175][176] For instance, Jeszenszki et al scrutinized the importance of a singlet-triplet mixture of geminals in APSG to properly describe the spin coupling between high-spin centers during multiple-bond dissociation processes.…”

Revealing the Structure–Interaction–Dissolubility Relationships through Computational Investigation Coupled with Solubility Measurement: Toward Solvent Design for Organosulfide Capture

“…The present investigation is focused on the molecular design of potential solvents for organosulfide removal via unlocking the relationships among molecular structures, weak solute− solvent interactions, and dissolubility. 15 Herein, a series of compounds having distinct molecular structures with different basic functional groups were selected as representatives from the overall chemical space. These compounds were collected considering two aspects.…”