Mixed quantum-classical methods for polaron spectral functions

Area of Science:

• Condensed Matter Physics
• Quantum Chemistry
• Computational Materials Science

Background:

• The spectral function is crucial for interpreting angle-resolved photoemission spectroscopy (ARPES) experiments.
• Understanding electron-phonon interactions is key to describing charge transport in materials.

Purpose of the Study:

• To investigate and compare the performance of two semiclassical methods: the mean-field Ehrenfest method and the mapping approach to surface hopping.
• To evaluate these methods for calculating the spectral function of a single charge interacting with phonons on a lattice.
• To assess their applicability to ab initio polaron models.

Main Methods:

• Semiclassical dynamics simulations.
• Mean-field Ehrenfest method.
• Mapping approach to surface hopping.
• Investigation of the one-dimensional Holstein model.

Main Results:

• Both the mean-field Ehrenfest method and the mapping approach to surface hopping were applied to calculate spectral functions.
• The performance of these methods was compared across varying electron-phonon coupling strengths and lattice sizes.
• The study identified the relative strengths and weaknesses of each semiclassical approach.
• Demonstrated efficient and accurate application to ab initio polaron models.

Conclusions:

• Semiclassical approaches offer a computationally inexpensive route to calculating spectral properties in electron-phonon-coupled systems.
• These methods provide encouraging accuracy for realistic material simulations.
• The findings facilitate the study of polarons and related phenomena in condensed matter systems.