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 shares 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 does not compensate the marginal improvements compared w

SUBMITTER: Kossoski F 

PROVIDER: S-EPMC9125689 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature