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Session Q12 - DCMP: DENSITY FUNCTIONAL THEORY
Mixed session, Friday morning, March 24, 8:00
Room C1, San Jose Convention Center
The long range behavior of the density of a finite system containing N electrons, \displaystyle n_N(r) , in its non-degenerate ground state is well-known. Less well-known is the behavior of the pair density, P(r,r') , as r'\to\infty , where P(r,r')\ d^3 r\ d^3 r' is the probability of finding an electron in d^3 r around r , and another in d^3 r' around r' . More than a decade ago, it was shown M. Levy, John P. Perdew, and Viraht Sahni, Phys. Rev. A 30, 2745 (1984). that \displaystyle \lim_r'\to\infty P(r,r') = n_N(r')\ n_N-1 (r) . If the N-1 particle system has a degenerate ground state, then the density n_N-1(r) which appears above also depends on the direction of r' . We demonstrate the validity of this result by extracting the N-1 particle density from the exact pair density for several systems. We also show that the local spin density (LSD) approximation of density functional theory, which works extremely well at small interelectronic separations, fails to reproduce this behavior. (Work supported by NSF grant DMR92-13755, and by `Deutsche Forschungsgemeinschaft')