Density-functional study of small molecules within the Krieger-Li-Iafrate approximation

Abstract

We report density-functional studies of several small molecules $({\mathrm{H}}_{2},$ ${\mathrm{N}}_{2},$ CO, ${\mathrm{H}}_{2}\mathrm{O},$ and ${\mathrm{CH}}_{4})$ within the Krieger-Li-Iafrate (KLI) approximation to the exact Kohn-Sham local exchange potential, using a three-dimensional real-space finite-difference pseudopotential method. It is found that the exchange-only KLI approximation leads to markedly improved eigenvalue spectra compared to those obtained within the standard local-density approximation (LDA), the generalized gradient approximation (GGA), and the Hartree-Fock (HF) method. For structural properties, exchange-only KLI approximation results are close to the corresponding HF values. We find that the addition of LDA or GGA correlation energy functionals does not lead to systematic improvements.

Locations

• Physical Review A - View
• arXiv (Cornell University) - View - PDF
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