Benchmarking the Exponential Ansatz for the Holstein model

TL;DR

This paper evaluates the effectiveness of the exponential ansatz in modeling the ground-state wavefunction of polarons within the Holstein model, providing benchmarks to inform future wavefunction development.

Contribution

It systematically benchmarks exponential ansatz variants for the Holstein model, guiding future research in polaron wavefunction approaches beyond single-electron systems.

Findings

Exponential ansatz variants show varying accuracy across parameter space.

Benchmark results highlight strengths and limitations of each approach.

Guidelines for future polaron wavefunction development are provided.

Abstract

Polarons are quasiparticles formed as a result of lattice distortions induced by charge carriers. The single-electron Holstein model captures the fundamentals of single polaron physics. We examine the power of the exponential ansatz for the polaron ground-state wavefunction in its coupled cluster, canonical transformation, and (canonically transformed) perturbative variants across the parameter space of the Holstein model. Our benchmark serves to guide future developments of polaron wavefunctions beyond the single-electron Holstein model.