Coulomb interactions between dipolar quantum fluctuations in van der Waals bound molecules and materials

Abstract

Mutual Coulomb interactions between electrons lead to a plethora of interesting physical and chemical effects, especially if those interactions involve many fluctuating electrons over large spatial scales. Here, we identify and study in detail the Coulomb interaction between dipolar quantum fluctuations in the context of van der Waals complexes and materials. Up to now, the interaction arising from the modification of the electron density due to quantum van der Waals interactions was considered to be vanishingly small. We demonstrate that in supramolecular systems and for molecules embedded in nanostructures, such contributions can amount to up to 6 kJ/mol and can even lead to qualitative changes in the long-range van der Waals interaction. Taking into account these broad implications, we advocate for the systematic assessment of so-called Dipole-Correlated Coulomb Singles in large molecular systems and discuss their relevance for explaining several recent puzzling experimental observations of collective behavior in nanostructured materials.

Interactions between large molecules pose a puzzle for reference quantum mechanical methods

“…In addition, we consider a larger system of a C 60 buckyball inside a [6]-cycloparaphenyleneacetylene ring (which we label as C 60 @[6]CPPA), consisting of 132 atoms. This structure has a number of interesting features: (i) an open-framework that can be found in covalent organic frameworks and carbon nanotubes, (ii) the buckyball has a large polarizability (76 ± 8 Å 3 ) 29 which gives rise to considerable dispersion interactions, and (iii) confinement between the ring and the buckyball that may cause non-trivial longrange repulsive interactions 30,31 .…”

Comprehensive Quantum Framework for Describing Retarded and Non-Retarded Molecular Interactions in External Electric Fields

“…Specifically, the QDO model can quantitatively -within a few percent compared to explicit treatment of electrons -describe polarization and dispersion interactions [24,54,55] as well as accurately capture electron density redistribution induced by these interactions [61]. In addition, QDOs have been shown to provide a robust tool to describe vdW interactions under the influence of external charges as well as spatial confinement [4,13,16]. Finally, even though the QDO model describes distinguishable Drude particles bound to their own nuclei, it is possible to generalize this model to quantum bosonic statistics.…”

“…Despite the relatively large number of studies on molecular interactions in electric fields, a comprehensive understanding of this topic is still missing and some results remain controversial. For instance, there is still an ongoing debate on the interpretation of vdW interactions in spatially-confined systems as having either an electrostatic or a quantummechanical origin [14][15][16][17]. The unusual R −4 scaling of dispersion interactions in QED induced by an external field and recently presented in Ref.…”

“…Many of such fieldinduced phenomena are not yet part of textbook knowledge, even from the point of view of standard QM. For example, the qualitative change of vdW dispersion interactions induced by confinement of molecules in nanostructures or under inhomogeneous electric fields is a recent proposition [4,13,16].…”

Molecular Interactions Induced by a Static Electric Field in Quantum Mechanics and Quantum Electrodynamics

“…The stable structure and properties of biomolecules, nanostructured materials, and molecular solids are determined by a delicate balance between different intermolecular forces [1][2][3]. In many realistic systems, molecular interactions are substantially modified by solvents, cell membranes, ionic channels, and other environments [4][5][6][7]. A proper description of such environments demands robust approaches for modeling both nonretarded and retarded intermolecular interactions under arbitrary fields.…”