Dispersion forces between noble gas atoms

Abstract

The coefficients of the R " 6 , R ~8, and R ~'° terms in the series representation of the dispersion interaction between helium, neon, and argon at distance R are calculated using an elementary variation method.

R–8 Dispersion Interaction: Derivation and Application to the Effective Fragment Potential Method

“…Extending the approach to higher multipoles, the fluctuating dipole–quadrupole interaction results in the R –8 term in the dispersion energy. , Removing the limit to spherical systems such as atoms, the foundational work by Buckingham formulated the dispersion forces within the framework of intermolecular perturbation theory. , The equations were made practical by introducing the Unsöld approximation and expressing the equations in terms of static molecular polarizabilities. The formulation and importance of higher order dispersion terms have been discussed for some special cases (e.g., linear molecule and tetrahedral molecule). , In the late 1970s, Lekkerkerker et al extended an alternative approximate approach for dispersion forces, applying the Kirkwood variational method to higher order dispersion terms. − Instead of the Unsöld approximation, the Casimir–Polder formula was employed, in which the dispersion interaction is expressed in terms of dynamic polarizabilities over the imaginary frequency range. Using spherical tensor formalism, Wormer et al developed a closed expression for the long-range interaction (including dispersion) in which the orientational dependence is simplified. − Later, Wormer and co-workers also computed the dynamic polarizabilities using many-body perturbation theory. , Due to the limited computational power at the time, early developments of dispersion interactions, especially higher order contributions, focused on noble gas atoms, diatomics, and simple molecules like methane. ,,− Molecular polarizabilities were typically used, and certain higher order multipolar contributions could be omitted by symmetry arguments.…”

Tetrel Interactions from an Interacting Quantum Atoms Perspective

“…From the many types of interactions that are usually classified as non-covalent, hydrogen bonding A−H···D [13,14], where A is a group more electronegative that H and D is an entity able to act as an electron donor, is undoubtedly the best-known by all chemists. Besides hydrogen and halogen bonding [15,16] (possibly the best-known type of NCI after the former), other purported NCIs involving atoms of groups 14, 15, and 16 (and even rare gas atoms [17,18]) have recently received the names of tetrel, pnictogen [19,20], and chalcogen bonding, respectively, although some of these complexes were identified and characterized by different experimental techniques long before they were given these names [19]. In all of them, the 14, 15, or 16 group element, acting as an electron acceptor or electrophilic site, seeks the nucleophilic part of another system, for instance an atomic or molecular anion (F - ,Br - ,⋯,CN - , NC - ,N 3 −,⋯), a π− electron pair of a Lewis base, or a non-bonding electron pair of an arbitrary molecule.…”