Sub-system self-consistency in coupled cluster theory

Abstract

In this Communication, we provide numerical evidence indicating that the standard single-reference coupled-cluster (CC) energies can be calculated alternatively to its copybook definition. We demonstrate that the CC energies can be reconstructed by diagonalizing the effective Hamiltonians describing correlated sub-systems of the many-body system. In the extreme case, we provide numerical evidence that the CC energy can be reproduced through the diagonalization of the effective Hamiltonian describing sub-system composed of a single electron. These properties of CC formalism can be exploited to design protocols to define effective interactions in sub-systems used as a probe to calculate the energy of the entire system and introduce a new type of self-consistency for approximate CC approaches.

arXiv admin note: text overlap with arXiv:2111.03215

References in corpus (3)

• Is there evidence for exponential quantum advantage in quantum chemistry?
• Downfolding of many-body Hamiltonians using active-space models: extension of the sub-system embedding sub-algebras approach to unitary coupled cluster formalisms
• Three Lagrangians for the complete-active space coupled-cluster method

Cited by in corpus (3)

• A Perspective on Quantum Computing Applications in Quantum Chemistry using 25--100 Logical Qubits
• A static quantum embedding scheme based on coupled cluster theory
• Complete Active Space Iterative Coupled Cluster Theory