Clustered Graph Partitions Provide Compact Diabatic Bases for RCI-LC-DFTB Charge-Transfer Calculations
Year: 2026
Type: preprint
Abstract: Restriction-based configuration interaction long-range corrected self-consistent charge density functional tight binding (RCI-LC-DFTB) is an efficient approximate quantum chemical method that uses non-orthogonal diabatic states to describe molecular chargetransfer states. However, its practical performance depends on how the charge-localized diabatic states are selected. Here, we develop and compare two graph-based strategies for automated diabatic-basis construction: a discrete graph Fourier representation and a clustered biconnected-partition representation. Applications to benzene-assembly benchmark systems show that the discrete graph Fourier representation provides a systematic expansion that can require many diabatic states, whereas the clustered biconnected- partition representation gives a more compact and chemically interpretable basis. We further apply the clustered representation to a 16-residue aromatic oligoamide foldamer under an external electric field, demonstrating unit-resolved analysis of field-induced long-range charge localization. These results show that clustered graph partitions
Source: ChemRxiv
Authors: Ji Huang, Tim Kowalczyk, Daisuke Yokogawa
Institutions: The University of Tokyo, Western Washington University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G2264456587, G336374793
OpenAlex ID: W7211928714