Bond-Energy Calculations Of Cu2, Ag2, And Cuag With The Generalized Gradient Approximation
PHYSICAL REVIEW A(1991)
摘要
We have calculated the bond lengths and bond energies of Cu2, Ag2, and CuAg using nonlocal-density-functional theory with the generalized gradient approximation (GGA), in order to investigate the validity of GGA to metal molecules. In GGA, an exchange-correlation energy density is approximated by a function of electron density rho(r), and its coordinate differences partial-rho(r), which are not considered in the local-spin-density approximation (LSDA). We performed fully self-consistent calculations, considering all electrons: the molecular orbitals were expanded by a Slater-type atomic basis, and a nonrelativistic approximation was used. The calculated bond energies of Cu2, Ag2, and CuAg in GGA are 0.4 eV (15%), 0.34 eV (17%), and 0.38 eV (17%) smaller than those results in LSDA, so that GGA removes about 2/3 of the overestimated value of bond energies in LSDA.
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关键词
electron density,molecular orbital,density function theory
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