Bipolarons from long-range interactions: Singlet and triplet pairs in the screened Hubbard-Fröhlich model on the chain

Hague, J. P. and Kornilovitch, P. E. (2009). Bipolarons from long-range interactions: Singlet and triplet pairs in the screened Hubbard-Fröhlich model on the chain. Physical Review B, 80(5) 054301.

DOI: https://doi.org/10.1103/PhysRevB.80.054301

Abstract

We present details of a continuous-time quantum Monte Carlo algorithm for the screened Hubbard-Fröhlich bipolaron. We simulate the bipolaron in one dimension with arbitrary interaction range in the presence of Coulomb repulsion, computing the effective mass, binding energy, total number of phonons associated with the bipolaron, mass isotope exponent, and bipolaron radius in a comprehensive survey of the parameter space. We discuss the role of the range of the electron-phonon interaction, demonstrating the evolution from Holstein to Fröhlich bipolarons and we compare the properties of bipolarons with singlet and triplet pairing. Finally, we present simulations of the bipolaron dispersion. The bandwidth of the Fröhlich bipolaron is found to be broad and the decrease in bandwidth as the two polarons bind into a bipolaron is found to be far less rapid than in the case of the Holstein interaction. The properties of bipolarons formed from long-range electron-phonon interactions, such as light strongly bound bipolarons and intersite pairing when Coulomb repulsion is large, are found to be robust against screening, with qualitative differences between Holstein and screened Fröhlich bipolarons found even for interactions screened within a single lattice site.

Viewing alternatives

Metrics

Item Actions

Export

You can export this page using these formats Digital Object Identifier - DOI