## Abstract The spatial exchange interaction, arising from the exchange‐type two‐electron integrals ( $ i\_pj\_q|i\_p^\prime j\_q^\prime $) between two different groups P and Q, is another driving force for the delocalization of π‐electrons besides orbital charge‐transfer and exchange interactions.
Performance of the Harris functional for extended basis sets at the Hartree–Fock and density functional levels
✍ Scribed by John Cullen
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 153 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
The Harris functional is a noniterative variational procedure that uses an input charge density to produce an energy that is surprisingly accurate compared to the converged Kohn-Sham self-consistent result. We adapted and generalized this functional for the Hartree-Fock closed- and open-shell cases as well as examined its use for hybrid density functional methods such as B3LYP. Analysis of extended basis set calculations shows that at the B3LYP level an input density formed from a double zeta + polarization orbital basis is accurate enough to reproduce the energy of triple zeta + double polarization + diffuse orbital basis. For large molecules this translates into a computational speed that can be an order of magnitude faster. In the case of Hartree-Fock calculations a "bootstrapping technique" that employs successive applications of the Harris functional can further reduce computational times while retaining sufficient accuracy.
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