Mori generalized master equations offer an efficient route to predict and interpret transport

TL;DR

This paper introduces a Mori-based generalized quantum master equation approach that efficiently predicts both DC and AC transport properties in small-polaron systems, reducing computational costs and providing microscopic insights from frequency data.

Contribution

The authors develop a single-calculation GQME method for transport prediction that includes derivatives for efficiency and introduce a cumulant analysis to connect experimental data with microscopic parameters.

Findings

Method reduces computational cost by up to 90%.

GQME accurately predicts frequency-resolved conductivity.

Cumulant analysis reveals limitations of the Drude-Smith model.

Abstract

Predicting how a material's microscopic structure and dynamics determine its transport properties remains a fundamental challenge. To alleviate this task's often prohibitive computational expense, we propose a Mori-based generalized quantum master equation (GQME) to predict the frequency-resolved conductivity of small-polaron forming systems described by the dispersive Holstein model. Unlike previous GQME-based approaches to transport that scale with the system size and only give access to the DC conductivity, our method requires only one calculation and yields both the DC and AC mobilities. We further show to easily augment our GQME with numerically accessible derivatives of the current to increase computational efficiency, collectively offering computational cost reductions of up to $90\%$, depending on the transport regime. Finally, we leverage our exact simulations to demonstrate the limited applicability of the celebrated and widely invoked Drude-Smith model in small-polaron forming systems. We instead introduce a cumulant-based analysis of experimentally accessible frequency data to infer the microscopic Hamiltonian parameters. This approach promises to provide valuable insights into material properties and facilitate guided design by linking macroscopic terahertz measurements to the microscopic details of small polaron-forming systems.