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Updated: Aug 26, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Electron localization functions obtained from X-ray constrained Hartree-Fock wavefunctions for molecular crystals of
Dylan Jayatilaka1, Daniel Grimwood
1Chemistry, School of Biomedical and Chemical Sciences, University of Western Australia, Crawley 6009, Australia. dylan@theochem.uwa.edu.au
Abstract:
Constrained Hartree-Fock wavefunctions in the superposition of isolated molecules model have been calculated from precise X-ray diffraction data on crystals of ammonia (NH(3)), urea [CO(NH(2))(2)] and alloxan [(CO)(4)(NH)(2)]. The X-ray constrained wavefunctions have been used to derive and examine 'electron localization' information, quantified by the true and approximate electron localization function (ELF), and the true and approximate Fermi hole mobility function (FHMF). The plots of the Fermi hole mobility function are the first to appear in the literature. The results are compared with corresponding isolated-molecule Hartree-Fock calculations to gauge the effect of the crystal environment on the isolated molecules. An error analysis is performed to indicate the features in the plots which are well determined from the experimental data. The results from all plots are broadly consistent, but the approximate ELF shows some artifacts relative to the true ELF.
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