Adapted Su-Schrieffer-Heeger Hamiltonian for polypyrrole

Abstract

A generic class of Hamiltonians based on the Su-Schrieffer-Heeger ͑SSH͒ model is introduced to address the material-specific properties of conducting polymers beyond polyacetylene. Two physical parameters are incorporated into the original SSH model Hamiltonian, one being the scaling parameter ␥ accounts for the modified electron-phonon coupling strength of aromatic rings and the other parameter representing the attractive cores of heterogeneous atoms, such as NH, S, and O. Their values are uniquely determined by two independent measurements, such as the experimental band gap of bulk polypyrrole ͑PPy͒ and the dimerization amplitude of pyrrole monomer computed by ab initio coupled cluster methods as chosen in this work. With the optimized values of ͕␥ = 1.46, = 4.27 eV͖, the adapted SSH ͑aSSH͒ Hamiltonian accurately reproduces the band gaps, molecular geometries, quasiparticle energies and wave functions, order parameters, discretized phonons around nonlinear polarons, and infrared and Raman spectra of both neutral and p-doped PPy chains of all lengths. It is expected that the generic formalism of the aSSH Hamiltonian, equipped with their corresponding ͕␥ , ͖ values, would be applicable to other conducting polymers, such as polythiophene, polyfuran, poly-͑p-phenylene-vinylene͒, polyaniline, and their functional derivatives.

Theory of anomalous magnetotransport from mass anisotropy

“…Large variations of the quasiparticle effective mass may simply occur from band structure effects (such as proximity to a van Hove singularity [14,15]), but also from fluctuations which renormalize the band structure. An example is in metals proximate to a density wave instability.…”

A constrained variational approach to the designing of low transport band gap materials: A multiobjective random mutation hill climbing method

“…Let H(R) represent the π -electron Hamiltonian describing the PT or PSe systems within the framework of a modified Su-Schrieffer-Heeger (SSH) model [9,10,[19][20][21], where R denotes the geometrical parameters (atom-atom distances) needed for completely defining H(R) in a basis of 2p z orbitals of the carbon atoms and 3p z (4p z ) orbitals of the sulfur (selenium) atoms. The π MOs (φ i ) are formed by linear combination of the carbon 2p z and sulfur 3p z (selenium 4p z ) orbitals:…”

In-situ chemical co-precipitation composition of hybrid precursors and luminescence of Y1−xGdxNbO4: RE3+ (RE=Tb, Eu) micron crystalline phosphors

“…It consists of a strong band centered at 260 nm and a weak band around 223 nm. The former originates from the transitions toward the charge transfer state (CTS) corresponding to Eu 3+ -O 2− interactions, the latter may be ascribed to the charge transfer transition from the oxygen ligands to the central metal atoms inside the NbO 4 3− groups [22,26]. Fig.…”

“…E-mail address: bingyan@tongji.edu.cn (B. Yan). doped with Tb 3+ was synthesized by via the high-temperature solid state method and studied their luminescent spectra [22]; optical properties of YNbO 4 doped with Eu 3+ phosphor was reported that the characteristic emission of rare earth ions Eu 3+ was detected and total or partial quenching of the NbO 4 3− emission occured because of the energy transfer from the matrix to the dopant [23][24][25][26].…”