NEUTRAL-IONIC INTERFACE IN ORGANIC CHARGE-TRANSFER SALTS

被引:79
作者
SOOS, ZG
MAZUMDAR, S
机构
[1] Department of Chemistry, Princeton University, Princeton
关键词
D O I
10.1103/PhysRevB.18.1991
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Charge transfer (CT) stabilization in linear stacks D+A-D+A- of -electron donors (D) and acceptors (A) involve spin-dependent configuration interactions that are treated exactly in rings of N=4, 6, 8, 10 sites, and extrapolated to N, by adapting valence-bond techniques to electron-hole excitations. The ground state CT (z) and the magnetic gap Em(z)2|t| to the lowest triplet are computed for arbitrary z=2|t|, where -2 is the energy for DAD+A-, -|t|=D+A-|H|DA is the Mulliken CT integral, and D2+, A2- sites are excluded. The spin degeneracy of A- and D+ ion radicals is treated exactly. Instead of the discontinuous change from =0 to =1 in the limit |t|0, finite overlap gives a continuous (z) and (zc)=0.680.01 at the neutral-ionic interface zc=0.530.01. The magnetic gap Em is finite for z<zc and vanishes for z>zc, where there is a diamagnetic to paramagnetic transition and the ground state switches from k=0 to k= symmetry. Collective effects due to long-range three-dimensional Coulomb interactions are included in a Hartree approximation and produce a first-order transition, with discontinuous (z), when the critical value m2|t|=1.40.1 of the Madelung stabilization m of a dimer is exceeded. The puzzling magnetic gaps in paramagnetic organic CT salts with mixed regular stacks arise naturally for partial CT and z<zc. Valence-bond analysis of CT excitations models the physical properties of organic complexes with overlapping sites and intermediate. © 1978 The American Physical Society.
引用
收藏
页码:1991 / 2003
页数:13
相关论文
共 47 条
[21]   COLLECTIVE ELECTRONIC STATES IN MOLECULAR CRYSTALS [J].
KRUGLER, JI ;
MONTGOMERY, CG ;
MCCONNELL, HM .
JOURNAL OF CHEMICAL PHYSICS, 1964, 41 (08) :2421-+
[22]  
KURODA H, 1968, B CHEM SOC JPN, V41, P1998
[23]   2 SOLUBLE MODELS OF AN ANTIFERROMAGNETIC CHAIN [J].
LIEB, E ;
SCHULTZ, T ;
MATTIS, D .
ANNALS OF PHYSICS, 1961, 16 (03) :407-466
[24]   CHARGE TRANSFER IN MOLECULAR CRYSTALS [J].
MCCONNEL.HM ;
HOFFMAN, BM ;
METZGER, RM .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1965, 53 (01) :46-&
[26]  
METZGER RM, 1975, J CHEM PHYS, V63, P5098, DOI 10.1063/1.431317
[27]  
METZGER RM, UNPUBLISHED
[28]  
MOROSIN B, UNPUBLISHED
[29]  
MULLIKEN RS, 1969, MOL COMPLEXES, P127
[30]   SPIN EXCITATIONS IN IONIC MOLECULAR CRYSTALS [J].
NORDIO, PL ;
SOOS, ZG ;
MCCONNEL.HM .
ANNUAL REVIEW OF PHYSICAL CHEMISTRY, 1966, 17 :237-+