Materials Research Lectures

The interaction between charge carriers and lattice vibrations in solids, also known as electron-phonon (e-ph) interaction, controls a range of physical processes including charge transport, excited carrier dynamics, ultrafast spectroscopy and superconductivity. Conventional e-ph calculations rely on empirical treatments that lack predictive power and quantitative accuracy. Ab initio calculations of the e-ph interaction using density functional theory and related methods are a recent focus in computational solid state physics; these novel e-ph calculations forego empirical parameters and can accurately predict materials properties controlled by e-ph processes.

This talk will introduce the theory of the e-ph interaction, together with its first-principles numerical implementation. Our recently developed algorithms to compute and interpolate the e-ph scattering rates will be presented. We will demonstrate application of e-ph calculations to charge transport and ultrafast excited carrier dynamics in metals, elemental and III-V polar semiconductors, and insulators. Presented results range from computing the resistivity of a material with high accuracy to computing the timescale and detailed mechanism of excited carrier energy loss. Code development efforts, open problems and future directions will be outlined.

More about the Speaker: Prof. Bernardi holds a B.S. from the University of Rome "La Sapienza", and a M.S. in Materials Science from the University of Rome "Tor Vergata" in Italy. He obtained his Ph.D. in Materials Science from MIT, where he worked with Prof. Jeff Grossman on novel materials and physical processes in solar energy conversion. He was a postdoc in the Physics Department at UC Berkeley, where he worked with Prof. Steve Louie and Prof. Jeff Neaton on excited electrons in materials. His group at Caltech focuses on computing the dynamics of excited states in materials, with applications to ultrafast optical processes and solar energy conversion. Prof. Bernardi has received a number of awards, including the 2015 Psi-K Volker Heine Young Investigator Award for electronic structure calculations, the Intel Ph.D. Fellowship from Intel, and the Endeavour Research Fellowship from the Australian Government, among others. His research has been featured in a number of magazines, including Wired, Nature, Scientific American, and Technology Review.