## Colloquium: Dr. Marco Bernardi, CALTECH

__TITLE:__Electron Dynamics in Materials from First Principles

__ABSTRACT:__

Calculations of charge transport and ultrafast dynamics have relied on heuristic approaches for the past several decades. Recent progress in combining density functional theory and related methods with the Boltzmann transport equation (BTE) are enabling spectacular advances in computing carrier dynamics in materials from first principles. The interaction between charge carriers and lattice vibrations, also known as electron-phonon (e-ph) interaction, plays a central role as it dominates carrier dynamics near room temperature and at low energy.

We will discuss our recently developed methods to compute e-ph scattering processes from first principles, and show how these advances enable accurate calculations of charge transport and ultrafast dynamics in materials, including:

1) Accurate calculations of the carrier mobility, leading to new insight into charge transport in semiconductors [1,2] and complex oxides [3,4]. We will focus on charge transport in SrTiO3 and complex oxides with structural phase transitions and polarons. We will also discuss briefly precise first-principles calculations of electron spin relaxation [5].

2) The ultrafast dynamics of excited carriers, with application to ultrafast spectroscopy and optoelectronics [6]. We will discuss a new approach to propagate in time the BTE for coupled excited electrons and phonons, and show its application to bulk and 2D materials.

We will outline code development efforts, open problems and future directions.