Effects of lattice geometry and interaction range on polaron dynamics

TL;DR

This study investigates how lattice geometry and interaction range influence polaron properties using quantum Monte Carlo simulations across various Bravais lattices, revealing the impact of dimensionality and coordination number on polaron dynamics.

Contribution

It provides a comprehensive analysis of polaron behavior on different lattices, comparing Holstein and Froehlich models, and explores the effects of interaction range on polaron mobility and spectral features.

Findings

Polaron effective mass increases with coordination number at strong coupling.

Spectral properties vary with lattice type and dimensionality.

Interaction range reduces the importance of coordination number.

Abstract

We study the effects of lattice type on polaron dynamics using a continuous-time quantum Monte-Carlo approach. Holstein and screened Froehlich polarons are simulated on a number of different Bravais lattices. The effective mass, isotope coefficients, ground state energy and energy spectra, phonon numbers, and density of states are calculated. In addition, the results are compared with weak and strong coupling perturbation theory. For the Holstein polaron, it is found that the crossover between weak and strong coupling results becomes sharper as the coordination number is increased. In higher dimensions, polarons are much less mobile at strong coupling, with more phonons contributing to the polaron. The total energy decreases monotonically with coupling. Spectral properties of the polaron depend on the lattice type considered, with the dimensionality contributing to the shape and the coordination number to the bandwidth. As the range of the electron-phonon interaction is increased, the coordination number becomes less important, with the dimensionality taking the leading role.