Density-functional Study of Small Molecules within the Krieger-Li-Iafrate Approximation
نویسندگان
چکیده
We report density-functional studies of several small molecules (H2, N2, CO,H2O, and CH4) within the Krieger-Li-Iafrate (KLI) approximation to the exact Kohn-Sham local exchange potential, using a threedimensional real-space finite-difference pseudopotential method. It is found that exchange-only KLI 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 results are close to the corresponding HF values. We find that the addition of LDA or GGA correlation energy functionals to the KLI exact exchange energy functional does not lead to systematic improvements. PACS numbers: 02.70Bf, 31.10.+z, 31.15.Ew, 31.15.Fx, 31.50.+w, 31.90+s Typeset using REVTEX
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