Reaction barriers on non-conducting surfaces beyond periodic local MP2: Diffusion of hydrogen on α-Al2O3(0001) as a test case

Abstract

The quest for “chemical accuracy” is becoming more and more demanded in the field of structure and kinetics of molecules at solid surfaces. In this paper, as an example, we focus on the barrier for hydrogen diffusion on a α-Al2O3(0001) surface, aiming for a couple cluster singles, doubles, and perturbative triples [CCSD(T)]-level benchmark. We employ the density functional theory (DFT) optimized minimum and transition state structures reported by Heiden, Usvyat, and Saalfrank [J. Phys. Chem. C 123, 6675 (2019)]. The barrier is first evaluated at the periodic Hartree–Fock and local Møller–Plesset second-order perturbation (MP2) level of theory. The possible sources of errors are then analyzed, which includes basis set incompleteness error, frozen core, density fitting, local approximation errors, as well as the MP2 method error. Using periodic and embedded fragment models, corrections to these errors are evaluated. In particular, two corrections are found to be non-negligible (both from the chemical accuracy perspective and at the scale of the barrier value of 0.72 eV): the correction to the frozen core-approximation of 0.06 eV and the CCSD(T) correction of 0.07 eV. Our correlated wave function results are compared to barriers obtained from DFT. Among the tested DFT functionals, the best performing for this barrier is B3LYP-D3.

Investigating the Basis Set Convergence of Diagrammatically Decomposed Coupled-Cluster Correlation Energy Contributions for the Uniform Electron Gas

“…In particular, at the truncation level of single, double, and perturbative triple particle-hole excitation operators, CCSD­(T) theory predicts atomization and reaction energies for a large number of molecules with an accuracy of approximately 1 kcal/mol . Although the computational cost of CCSD­(T) theory is significantly larger than that of the more widely used approximate density functional theory calculations, recent methodological developments enable the study of relatively complex systems, for instance, molecules adsorbed on surfaces. − However, high accuracy compared to experiment can only be achieved if the ansatz is fully converged with respect to all computational parameters that model the true physical system. These include the number of atoms used to model an infinitely large periodic crystal and the truncation parameter of the basis set.…”

Cluster-in-Molecule Method Combined with the Domain-Based Local Pair Natural Orbital Approach for Electron Correlation Calculations of Periodic Systems

“…A few local correlation methods have been extended to periodic systems as well, among which the local-MP2 (LMP2) with periodic boundary conditions (PBCs) represents a particularly important milestone. − Most recently, a few flavors of CC − and FCIQMC have also been proposed and implemented with the aid of the embedding techniques. , In all these approaches, localized Wannier functions (WFs) play an essential role. , Wave function-based incremental method − is also an efficient framework for electron correlation calculations of extended systems.…”