Lattice embedding and equilibrium geometry of metal-halogen chains in the two-band extended Hubbard model

Anusooya, Y.; Ramasesha, S.

doi:10.1007/bf02840761

Cited by 1 publication

(2 citation statements)

References 19 publications

(15 reference statements)

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“…Coulson's formula for polyenes, for example, gives a direct relation between bond orders and bond lengths. For small systems, our earlier studies [16], carried out incorporating the distortion of the chain self-consistently, show that the distortion given by a formula similar to Coulson's formula gives bond lengths very close to equilibrium bond lengths even at the first iteration. Therefore, the excess-charge-density distribution together with bond-order patterns in the chain will give us information about the nature of the states produced upon doping.…”

Section: Chains Marginally Away From Three-quarters Fillingmentioning

confidence: 90%

“…They found relative lattice distortion around the defect centre besides the charge or spin disproportionation. The effect of interchain interactions on the nature of the ground state and also on the energy gaps in the system were studied by including them self-consistently in finite-MX-chain calculations, within a two-band model [16]. The effect of interchain interactions on the stability of nonlinear lattice relaxation was considered by Mishima [17] in the mean-field approximation within the one-band extended Hubbard-Peierls model.…”

Section: Introductionmentioning

confidence: 99%

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Density-matrix renormalization group studies of metal-halogen chains within a two-band extended Peierls-Hubbard model

Anusooya¹,

Pati²,

Ramasesha³

1999

J. Phys.: Condens. Matter

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The phase diagram of halogen-bridged mixed-valent metal complexes (M X) has been studied using a two-band extended Peierls-Hubbard model employing the recently developed Density Matrix Renormalization Group method. We present the energies, charge and spin density distributions, bond orders, charge-charge and spin-spin correlations, in the ground state for different parameters of the model. The effect of bond alternation and site-diagonal distortion on the ground state properties are considered in detail. We observe that the site-diagonal distortion plays a significant role in deciding the nature of the ground state of the system. We find that while the CDW and BOW phases can coexist, the CDW and SDW phases are exclusive in most of the cases. We have also studied the doped M X chains both with and without bond alternation and site-diagonal distortion in the CDW as well as SDW regimes. We find that the additional charge in the polarons and bipolarons for hole doping are confined to a few sites, in the presence of bond alternation and site-diagonal distortion. For electron doping, we find that the additional charge(s) is(are) smeared over the entire chain length and although energetics imply a disproportionation of the negatively charged bipolaron, the charge and spin density distributions do not reflect it. Positively charged bipolaron disproportionates into two polarons in the SDW region. There is also bond order evidence for compression of bond length for the positively charged polaronic and bipolaronic systems and an elongation of the bonds for systems with negatively charged polarons and bipolarons.

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Section: Chains Marginally Away From Three-quarters Fillingmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%