Hierarchy Configuration Interaction: Combining Seniority Number and Excitation Degree

Abstract

We propose a novel partitioning of the Hilbert space, hierarchy configuration interaction (hCI), where the excitation degree (with respect to a given reference determinant) and the seniority number (i.e., the number of unpaired electrons) are combined in a single hierarchy parameter. The key appealing feature of hCI is that each hierarchy level accounts for all classes of determinants whose number share the same scaling with system size. By surveying the dissociation of multiple molecular systems, we found that the overall performance of hCI usually exceeds or, at least, parallels that of excitation-based CI. For higher orders of hCI and excitation-based CI, the additional computational burden related to orbital optimization usually do not compensate the marginal improvements compared with results obtained with Hartree-Fock orbitals. The exception is orbital-optimized CI with single excitations, a minimally correlated model displaying the qualitatively correct description of single bond breaking, at a very modest computational cost.

arXiv comment7 pages, 3 figures (supporting information available)

References in corpus (23)

• A Mountaineering Strategy to Excited States: Highly-Accurate Reference Energies and Benchmarks
• Towards the solution of the many-electron problem in real materials: equation of state of the hydrogen chain with state-of-the-art many-body methods
• Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs
• Seniority-based coupled cluster theory
• QUESTDB: a database of highly-accurate excitation energies for the electronic structure community
• Efficient description of strongly correlated electrons with mean-field cost
• Selected configuration interaction dressed by perturbation
• Fixed-Node Diffusion Monte Carlo potential energy curve of the fluorine molecule F2 using selected configuration interaction trial wavefunctions
• Projected seniority-two orbital optimization of the Antisymmetric Product of one-reference orbital Geminal
• A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Exotic Molecules and Radicals
• Ground-state properties of the hydrogen chain: insulator-to-metal transition, dimerization, and magnetic phases
• Linearized Coupled Cluster Correction on the Antisymmetric Product of 1 reference orbital Geminals
• Excited States From State Specific Orbital Optimized Pair Coupled Cluster
• Pair extended coupled cluster doubles
• Excited states with selected CI-QMC: chemically accurate excitation energies and geometries
• Variational coupled cluster for ground and excited states
• Accurate full configuration interaction correlation energy estimates for five- and six-membered rings
• Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction
• Tailoring CIPSI expansions for QMC calculations of electronic excitations: the case study of thiophene
• Is Externally Corrected Coupled Cluster Always Better than the Underlying Truncated Configuration Interaction?
• $\Delta$NO and the complexities of electron correlation in simple hydrogen clusters
• Bivariational Principle for an Antisymmetrized Product of Nonorthogonal Geminals Appropriate for Strong Electron Correlation
• Near-exact treatment of seniority-zero ground and excited states with a Richardson-Gaudin mean-field