On the charge distribution and the lattice distortion of quasi-one-dimensional systems
Electrostatic energy and electronic structure of donor-acceptor molecular crystals based on tetracyanquinodimethane is considered. The ground state energy of quasi-one-dimensional systems consisting of electron donors (TTF, NMP, 8b) and acceptors (TCNQ) is calculated. It is shown that for TTF-TCNQ, NMP-TCHQ, and Rb-TCNQ crystals the dominant contribution is made by the electrostatic energy. The electrostatic energy (or Madelung energy) EM for these systems has been calculated numerically by the Evald method using the X-ray data on the structure of corresponding cry stals and molecular systems. The charge distributions in the molecules and ions under consideration (i.e. TCNQ(o,−), NMP(o,+), and TTF(o,+)) have been obtained from the PPP, CNDO/2 and INDO calculations.
It is shown that the total electron transfer from donors (D) to acceptors (A) is energetically disadvantageous for the TTF-TCNQ and NMP-TCNQ crystals. For these systems the Madelung energy per a pair D+A- is smaller than the
KeywordsGround State Energy Lattice Distortion Electrostatic Energy Adiabatic Limit Charged Defect
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- 1.R.Comes, G.Shirane, S.M.Shapiro, A.F.Garito, A.J.Heeger, Preprint, BNL-21110; 1976.Google Scholar
- 2.V.E.Klimenko, V.Ya.Krivnov, A.A.Ovchinnikov, I.I.Ukrainskii, A.F.Shvets. Zh. Exp. Theor. Phys. 62, 240 (1975).Google Scholar
- 3.I.I.Ukrainskii, V.E.Klymenko, A.A.Ovchinnikov, Preprint, ITP-75-89E, 1975, Phys. Stat. Sol. (in press), 1976.Google Scholar
- 4.A.A.Ovchinnikóv, Zh. Exp. Theor. Phys., 64, 342 (1973).Google Scholar
- 5.V.Ya.Krivnov, A.A.Ovchinnikov. Zh. Exp. Theor. Phys. (Letters), 21, 696 (1975).Google Scholar
- 6.H.Fröhlich, Phys. Rev. 79, 845 (1950) Proc. Roy. Soc., A223, 296 (1954).Google Scholar
- 7.J.Bardeen, D.Allender, J,W.Bray, Phys. Rev.B9,119/1974/.Google Scholar
- 8.K.B.Yefetov, A.I.Larkin, Zh. Exp. Theor. Phys. 69, 764 (1975).Google Scholar
- 9.T.Holatein,Ann.Phys.8,343,1959.Google Scholar