Surface Adsorption

van der Waals forces control ferroelectric–antiferroelectric ordering in CuInP2S6 and CuBiP2Se6 laminar materials

“… 43 Another is the value of 43 meV predicted by the many-body dispersion 33 , 34 (MBD) method, an advanced treatment of dispersion that, to treat conductors better, does not assume pairwise additivity; 44 it is also known to be widely robust to chemical scenario. 5 …”

“…The D3 correction takes on a “pairwise additive” form involving summation of London dispersion energies between every pair of atoms in the system. 5 , 28 , 44 Hence, in principle it is possible to decompose this contribution into terms arising from constituent atoms, and here we do this considering contributions from Cu to Cu interactions, Cu to non-Cu interactions, and non-Cu to non-Cu interactions using: …”

“… 3 A classic catalytic system is the very strong binding of benzene to copper surfaces, 4 a system traditionally believed to involve Cu–C covalent bonding that instead now forms a paradigm for the understanding of strong van der Waals forces. 5 The van der Waals force is well known as being critical to the control of self assembly, 6 , 7 hence strongly affecting many conceived devices made from 2D materials. Here, we show that strong specific van der Waals interactions associated with soft 8 , 9 copper ions go beyond this to control internal ferroelectric ordering in polar laminar materials containing sheets of soft sulfur or selenium atoms.…”

Faraday cage screening reveals intrinsic aspects of the van der Waals attraction

“…Studies of 2D materials are currently very prevalent, with first-principle simulations providing powerful tools to facilitate understanding ( 11 , 22 – 25 ). While dispersion interactions are critical for determining the structure and properties of such systems, the most commonly used method applied for first-principles materials simulations, density functional theory (DFT) using a conventional generalized-gradient approximation (GGA), improperly treats its contribution.…”

“…While dispersion interactions are critical for determining the structure and properties of such systems, the most commonly used method applied for first-principles materials simulations, density functional theory (DFT) using a conventional generalized-gradient approximation (GGA), improperly treats its contribution. As a result, a wide range of empirical correction schemes are commonly added to GGA calculations so as to produce a realistic description of the critical interactions ( 24 , 25 ). The vdW dispersion interactions described by these schemes typically involve sums over interatomic interactions, each described by the London force ( 21 , 26 – 28 ), with only small corrections.…”