Seniority-Zero Canonical Transformation Theory: Error Reduction via Late Truncation
Abstract
We show how to add the effects of residual electron correlation to a reference seniority-zero wave function by transforming the true electronic Hamiltonian into seniority-zero form. The transformation is treated via the Baker-Campbell-Hausdorff (BCH) expansion, and the seniority-zero structure of the reference is exploited to evaluate the first three commutators exactly; the remaining contributions are handled with a recursive commutator approximation, as is typical in canonical transformation methods. By choosing a seniority-zero reference and using parallel computation, this method is practical for small- to medium-sized systems. Numerical tests show high accuracy, with errors ∼10-4 Hartree.
Fields of Study & Subjects
Quantum and electron transport phenomena
Advanced Chemical Physics Studies
Quantum Mechanics and Non-Hermitian Physics
Publication details
- Journal / source
- Journal of Chemical Theory and Computation
- Publisher
- American Chemical Society (ACS)
- Volume
- 22
- Issue
- 4
- Pages
- 1748–1759
- Publication date
- 4 February 2026
- Language
- EN