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Asymptotic behavior of the RHF energy of the PPP model of alternant cyclic polyenes

✍ Scribed by G. L. Bendazzoli; S. Evangelisti

Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
216 KB
Volume
66
Category
Article
ISSN
0020-7608

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✦ Synopsis

The large N expansion of the restricted Hartree᎐Fock RHF exchange Ž .

Ž . energy per atom E N of the Pariser᎐Parr᎐Pople PPP model of cyclic polyenes Ž . annulenes C H is derived in detail. We explicitly derive the coefficients E and E of

simple case of half-filling and no bond alternation. The exchange energy per atom in the Ž 2 . ϱ Äw Ž . x wŽ . 2 x 4 infinite chain can be written as E s 2r Ý ␥ 2 j y 1 r 2 j y 1 , where ␥ is e x js1 ϱ ϱ the two-electron repulsion integral in the infinite chain. On the other hand, the second coefficient E giving a finite-size correction is found to be 1r2 b, where b is the bond 1 length. This value of E differs slightly from that of a linear chain with periodic 1 boundary conditions because the distance between sites depends upon the radius of the ring, i.e., upon N.

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