11 papers · 1 filter
The principle of detailed balance between electrons and phonons in presence of excitonic effects
Alberto Guandalini, Giovanni Caldarelli, Francesco Mauri +1
Based on a many-body formulation, we derive an electron-phonon coupling including excitonic effects that preserves thermodynamic detailed balance between electronic and phononic sc…
Elastic Constants and Bending Rigidities from Long-Wavelength Perturbation Expansions
Changpeng Lin, Samuel Poncé, Francesco Macheda +2
Mechanical and elastic properties of materials are among the most fundamental quantities for many engineering and industrial applications. Here, we present a formulation that is ef…
Spin-dependent anisotropic electron-phonon coupling in KTaO
Giulia Venditti, Francesco Macheda, Paolo Barone +2
KTaO (KTO) is an incipient ferroelectric, characterized by a softening of the lowest transverse optical (TO) mode with decreasing temperature. Cooper pairing in the recently di…
Excitonic effects in phonons: reshaping the graphene Kohn anomalies and lifetimes
Alberto Guandalini, Francesco Macheda, Giovanni Caldarelli +1
We develop an ab initio framework that captures the impact of electron-electron and electron-hole interactions on phonon properties. This enables the inclusion of excitonic effects…
Variational formulation of dynamical electronic response functions in presence of nonlocal exchange interactions
Giovanni Caldarelli, Alberto Guandalini, Francesco Macheda +1
We consider the dynamical electronic response function in theoretical frameworks that include nonlocal exchange interactions, such as the Bethe-Salpeter equation with the frequency…
First principles calculations of dynamical Born effective charges, quadrupoles and higher order terms from the charge response in large semiconducting and metallic systems
Francesco Macheda, Paolo Barone, Francesco Mauri
Within the context of first principles techniques we present a theoretical and computational framework to quickly determine, at finite momentum, the self-consistent (longitudinal)…