English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The many-body expansion (MBE) is an efficient tool which has a long historyof use for calculating interaction energies, binding energies, latticeenergies, and so on. In the past, applications of MBE to correlation energyhave been unfeasible for large systems, but recent improvements to computingresources have sparked renewed interest in capturing the correlation energyusing the generalized $n$-th order Bethe-Goldstone equation. In this work, weextend this approach, originally proposed for a Slater determinant, to a tensorproduct state (TPS) based wavefunction. By partitioning the active space intosmaller orbital clusters, our approach starts from a cluster mean fieldreference TPS configuration and includes the correlation contribution of theexcited TPSs using the many-body expansion. This method, named clustermany-body expansion (cMBE), improves the convergence of MBE at lower orderscompared to directly doing a block based MBE from a RHF reference. We presentnumerical results for strongly correlated systems such as the one- andtwo-dimensional Hubbard models and the chromium dimer. The performance of thecMBE method is also tested by partitioning the extended $\pi$ space of severallarge $\pi$-conjugated systems, including a graphene nano-sheet with a verylarge active space of 114 electrons in 114 orbitals, which would require$10^{66}$ determinants for the exact FCI solution.

Cluster many-body expansion: a many-body expansion of the electron correlation energy about a cluster mean-field reference