Piezoelectric Electron-Phonon Interaction from <i>Ab Initio</i> Dynamical Quadrupoles: Impact on Charge Transport in Wurtzite GaN
Vatsal A. Jhalani, Jin-Jian Zhou, Jinsoo Park, Cyrus E. Dreyer, Marco Bernardi
Abstract
First-principles calculations of $e\text{\ensuremath{-}}\mathrm{ph}$ interactions are becoming a pillar of electronic structure theory. However, the current approach is incomplete. The piezoelectric (PE) $e\text{\ensuremath{-}}\mathrm{ph}$ interaction, a long-range scattering mechanism due to acoustic phonons in noncentrosymmetric polar materials, is not accurately described at present. Current calculations include short-range $e\text{\ensuremath{-}}\mathrm{ph}$ interactions (obtained by interpolation) and the dipolelike Fr\"olich long-range coupling in polar materials, but lack important quadrupole effects for acoustic modes and PE materials. Here we derive and compute the long-range $e\text{\ensuremath{-}}\mathrm{ph}$ interaction due to dynamical quadrupoles, and apply this framework to investigate $e\text{\ensuremath{-}}\mathrm{ph}$ interactions and the carrier mobility in the PE material wurtzite GaN. We show that the quadrupole contribution is essential to obtain accurate $e\text{\ensuremath{-}}\mathrm{ph}$ matrix elements for acoustic modes and to compute PE scattering. Our work resolves the outstanding problem of correctly computing $e\text{\ensuremath{-}}\mathrm{ph}$ interactions for acoustic modes from first principles, and enables studies of $e\text{\ensuremath{-}}\mathrm{ph}$ coupling and charge transport in PE materials.