Local embedding of Coupled Cluster theory into the Random Phase Approximation using plane-waves

TL;DR

This paper introduces a plane-wave embedding method combining high-level Coupled Cluster theory with low-level RPA to accurately and efficiently treat local electron correlation effects in periodic systems, demonstrated on various adsorption and impurity calculations.

Contribution

A novel plane-wave embedding scheme integrating Coupled Cluster and RPA for periodic systems, enabling accurate local correlation treatment with improved convergence.

Findings

Accurate adsorption energies with errors below 20 meV.

Efficient treatment of long-range dispersion effects.

Application to large systems with over 1000 electrons.

Abstract

We present an embedding approach to treat local electron correlation effects in periodic environments. In a single, consistent framework, our plane-wave based scheme embeds a local high-level correlation calculation (here Coupled Cluster Theory, CC), employing localized orbitals, into a low-level correlation calculation (here the direct Random Phase Approximation, RPA). This choice allows for an accurate and effcient treatment of long-range dispersion effects. Accelerated convergence with respect to the local fragment size can be observed if the low-level and high-level long-range dispersion are quantitatively similar, as is the case for CC in RPA. To demonstrate the capabilities of the introduced embedding approach, we calculate adsorption energies of molecules on a surface and in a chabazite crystal cage, as well as the formation energy of a lattice impurity in a solid at the level of highly accurate many-electron perturbation theories. The absorption energy of a methane molecule in a zeolite chabazite, for instance, is converged with an error well below 20 meV at the CC level. As our largest periodic benchmark system, we apply our scheme to the adsorption of a water molecule on titania in a supercell containing more than 1000 electrons.