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    • Keywords

       

      Molecular orbitals; orbital energies; highest occupied molecular orbital (HOMO); lowest unoccupied molecular orbital (LUMO); band gap; molecular tailoring approach; Hartree-Fock (HF) theory; density functional theory (DFT).

    • Abstract

       

      Molecular orbitals (MO’s) within Hartree-Fock (HF) theory are of vital importance as they provide preliminary information of bonding and features such as electron localization and chemical reactivity. The contemporary literature treats the Kohn-Sham orbitals within density functional theory (DFT) equivalently to the MO's obtained within HF framework. The high scaling order of ab initio methods is the main hurdle in obtaining the MO's for large molecular systems. With this view, an attempt is made in the present work to employ molecular tailoring approach (MTA) for obtaining the complete set of MO's including occupied and virtual orbitals, for large molecules at HF and B3LYP levels of theory. The energies of highest occupied and lowest unoccupied molecular orbitals, and hence the band gaps, are accurately estimated by MTA for most of the test cases benchmarked in this study, which include 𝜋-conjugated molecules. Typically, the root mean square errors of valence MO's are in range of 0.001 to 0.010 a.u. for all the test cases examined. MTA shows a time advantage factor of 2 to 3 over the corresponding actual calculation, for many of the systems reported.

    • Author Affiliations

       

      Anuja P Rahalkar1 2 Shridhar R Gadre1

      1. Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India
      2. Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007, India
    • Dates

       
  • Journal of Chemical Sciences | News

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