Neutral-ionic interface in charge-transfer salts with long-range coulomb interactions
✍ Scribed by Z.G. Soos; S. Kuwajima
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- English
- Weight
- 374 KB
- Volume
- 122
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Coulomb inleraclions -Vol slabilize bolh neulral and ionic lattices against charge-m-m&r (CT) excitations for Madelung. conslam a>l. The neulral-ionic phase boundary 6,(x) and ioniciiy jump 4q(x) are accurately given by the lowest-order corrections in x = IrI/V(a-1) Tor x < 0.2 and Mull&en CT inwgal f. Numerical sohnions or (2N < 18)~sile DA rings. with D'+ and A'-excluded. show Aq(x) lo vanish for x > x, = 0.33kO.02, where S,/lrl= 0.39kO.01. in connas~ to 6, = 0 in Iwo-smte models thal negla1 the D' and Aspins. Solid charge-transfer (CT) complexes of z-electron donors (D) and acceptors (A) usually crystallize in mixed molecular stacks with MulIiken CT integrgral t = (D+A-I BLIDA) between neighbors [I]. The relative energies of diamagnetic neutral (. . .DADA.. _) and pammagnetic ionic (_ _ .D+AYD+A-. _ _) arrays depend on the donor's ionization potential I, the acceptor's electron afftity A, and the Madelung energy --Va per ion pair in the ionic lattice. Other intermolecular interactions are usually neglected_ Torrance and coworkers [2] have identified borderline complexes, notably TTF-Chloranil, with I-A = VQ and neutralionic (n-i) transitions with pressure or temperature_ The theoretical challenge is to include both It I> 0 and strong on-site and intersite Coulomb interactions.