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Influence of Coulomb-attenuation on exchange-correlation functional quality
Michael J G Peach1, Aron J Cohen, David J Tozer
1Department of Chemistry, University of Durham, South Road, Durham, UK DH1 3LE.
Physical Chemistry Chemical Physics : PCCP
|October 19, 2006
Summary
Investigating Coulomb-attenuated functionals reveals that while exact long-range conditions improve some properties, they hinder others. Further development is needed for optimal performance across all chemical property classes.
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Theoretical Chemistry
Background:
- Exchange-correlation functionals are crucial for density functional theory (DFT) accuracy.
- Coulomb attenuation aims to improve long-range interactions in functionals.
- Understanding the impact of attenuation parameters on functional performance is essential.
Purpose of the Study:
- To investigate the dependence of functional quality on attenuation parameters in Coulomb-attenuated exchange-correlation functionals.
- To evaluate the effect of satisfying exact long-range conditions on various chemical properties.
- To assess the performance of these functionals for different types of electronic excitations.
Main Methods:
- Systematic investigation of Coulomb-attenuated exchange-correlation functionals.
- Analysis of the influence of attenuation parameters controlling limiting values and rates.
- Evaluation of functional performance for atomization energies, bond lengths, reaction barriers, and electronic excitation energies (valence, Rydberg, intramolecular, and charge transfer).
Main Results:
- Satisfying exact long-range conditions is detrimental to atomization energies and bond lengths.
- These conditions improve classical reaction barriers and small molecule electronic excitation energies.
- Functionals show high quality for valence, Rydberg, and intramolecular charge transfer excitations, but not uniformly for all classes, especially asymptotic intermolecular charge transfer.
Conclusions:
- No single Coulomb-attenuated functional optimally describes all investigated chemical properties simultaneously.
- Charge transfer excitations are not consistently improved compared to conventional functionals.
- Further development of Coulomb-attenuated functionals is necessary to achieve broader accuracy.
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