Configuration weights in coupled-cluster theory

Abstract

We introduce a simple definition of the weight of any given Slater determinant in the coupled-cluster state, namely as the expectation value of the projection operator onto that determinant. The definition can be applied to any coupled-cluster formulation, including conventional coupled-cluster theory, perturbative coupled-cluster models, nonorthogonal orbital-optimized coupled-cluster theory, and extended coupled-cluster theory, allowing for wave-function analyses on par with configuration-interaction-based wave functions. Numerical experiments show that for single-reference systems the coupled-cluster weights are in excellent agreement with those obtained from the full configuration-interaction wave function. Moreover, the well-known insensitivity of the total energy obtained from truncated coupled-cluster models to the choice of orbital basis is clearly exposed by weights computed in the ${\hat{T}}_1$-transformed determinant basis. We demonstrate that the inseparability of the conventional linear parameterization of the bra (left state) for systems composed of noninteracting subsystems may lead to ill-behaved (negative or greater than unity) weights, an issue that can only be fully remedied by switching to extended coupled-cluster theory. The latter is corroborated by results obtained with quadratic coupled-cluster theory, which is shown numerically to yield a significant improvement.

50 pages, 4 figures

References in corpus (11)

• Climbing the Density Functional Ladder: Non-Empirical Meta-Generalized Gradient Approximation Designed for Molecules and Solids
• The Density Matrix Renormalization Group in Chemistry and Molecular Physics: Recent Developments and New Challenges
• Ab initio quantum dynamics using coupled-cluster
• Time-dependent optimized coupled-cluster method for multielectron dynamics
• Symplectic integration and physical interpretation of time-dependent coupled-cluster theory
• Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
• Interpretation of Coupled-Cluster Many-Electron Dynamics in Terms of Stationary States
• Demonstrating that the non orthogonal orbital optimized coupled cluster model converges to full configuration interaction
• What Can Quantum Information Theory Offer to Quantum Chemistry?
• The $S$-diagnostic -- an a posteriori error assessment for single-reference coupled-cluster methods
• Guaranteed convergence for a class of coupled-cluster methods based on Arponen's extended theory

Cited by in corpus (1)

• Chemical Interpretation of Time-Dependent Coupled-Cluster Theory