An ab Initio Study of van der Waals Potential Energy Parameters for Silver Clusters

Abstract

We employ ab initio calculations of van der Waals complexes to study the potential energy parameters (C(6) coefficients) of van der Waals interactions for modeling of the adsorption of silver clusters on the graphite surface. Electronic structure calculations of the (Ag(2))(2), Ag(2)-H(2), and Ag(2)-C(6)H(6) complexes are performed using a coupled-cluster approach that includes single, double, and perturbative triple excitations (CCSD(T)), Møller-Plesset second-order perturbation theory (MP2), and spin-component-scaled MP2 (SCS-MP2) methods. Using the atom pair approximation, the C(6) coefficients for silver-silver, silver-hydrogen, and silver-carbon atom systems are obtained after subtracting the energies of quadrupole-quadrupole interactions from the total electronic energy.

Combining density functional and incremental post-Hartree-Fock approaches for van der Waals dominated adsorbate-surface interactions: Ag2/graphene

“…In this way, an effective C 6 coefficient of 64.60 eV/Å 6 was obtained for the Ag-C atomic pair. 44 This value is in an impressive agreement (within 2%) with that obtained here with the incremental D * as approach (63.46 eV/Å 6 ).…”

“…The long-range electrostatic quadrupole-quadrupole interaction is attractive for the perpendicular structure and repulsive when the dimer axis is oriented parallel to the carbon-ring plane. 44 This is the reason of the very long-ranged attractive tail of the HF interaction energy for the perpendicular configuration (see Table I). At smaller Ag 2 /benzene distances, the non-negligible role of the inductive interaction due to the polarization of the Ag 2 dimer in a direction perpendicular to the surface becomes reflected in the shallow minimum of the HF potential energy curve that is absent for the parallel structure (see Fig.…”

“…A different approach has been developed by Halonen and collaborators 44 to extract the long-range vdW contribution by subtracting the electrostatic portion from the total CCSD(T) interaction energy. In this way, an effective C 6 coefficient of 64.60 eV/Å 6 was obtained for the Ag-C atomic pair.…”

“…Due to the inability of commonly used semi-local density functionals to describe long-range correlation effects, the explicit inclusion of dispersion corrections is the current standard in DFT-based calculations. During the last decade, different vdW-corrected DFT methods [39][40][41][42][43][44][45][46] (referred to as DFT + D) have been developed and implemented into periodic codes, with numerous applications to physisorption problems (for a recent review, see, e.g., Ref. 47).…”

Pair-Potential Approach to Accurate Dispersion Energies between Group 12 (Zn, Cd, Hg) Clusters

“…In this study, we focus on a simple scheme, − where the vdW interaction is calculated based on atomic dispersion coefficients extracted from small model systems. The dispersion coefficients calculated previously in ref are used to model the dispersion interaction in larger group 12 clusters.…”