How to resolve a phonon-associated property into contributions of basic phonon modes

Abstract

Many properties of materials are associated with phonons. To better understand the phonon-property relation, it is a common practice to decompose the phonon-associated property into the contributions of basic phonon/vibration modes (e.g. longitudinal/transverse acoustic/optical mode), and identify the mode(s) that dominate(s) the property. The existing methods rely on labelling the phonon into one of the basic modes (BMs), however, the vibration characteristics of many phonons are different from the definitions of BMs, indicating these methods may give wrong decomposition results. Here we present a new method based on treating the phonon as a mixture of the BMs. By aligning the wave vectors and then projecting the phonon eigenvector onto the eigenvectors of the BMs, we can obtain the weights of the BMs on the given phonon, which can be used to quantify the contribution of each BM to the property. As an example, we apply this method to unravel the phonon modes that dominate the scattering of the electrons at the conduction band edge in two-dimensional antimony, an emerging semiconductor that has attracted great interest for electronics, but its mobility-limiting factors remain unclear. We find that the electron scattering is dominated by the out-of-plane acoustic phonon mode followed by the longitudinal acoustic mode, which are different from the results of other methods. Our method is generally applicable to different kinds of phonon-related properties and to all crystal materials.

Revisiting the structural, electronic and photocatalytic properties of Ti and Zr based perovskites with meta-GGA functionals of DFT

“…Since lattice vibrations can provide additional momentum to charge carriers of indirect band gap materials 70 , phonons also play a key role in the interband transitions. For this reason, a reliable knowledge of the phonon modes in a perovskite photocatalyst can prove useful in designing improved absorption of electromagnetic radiations [71][72] as well as controlling electron-hole recombination rates [73][74] It is well know that the dielectric and ferroelectric properties of the cubic ABO 3 perovskite oxides are controlled by phonons 51,53,55,76 , which can be modified by varying stress or temperature. It is therefore intuitive to assess the performance of a DFT functional in predicting experimentally observed phonon modes and instabilities (e.g.…”

Correlation between Orbital Hybridizations, Phonon Spectra, and Thermal Properties of Graphene, Germanene, and Plumbene

“…The important factor characterizes the contribution of i vibration into the phonon branch with wave vector and band index j . [ 66 ] In order to determine , we constructed 400 000 points uniformly distributed over 1/12th part of the first Brillouin zone of group IV monolayers (blue area in Figure 2d) and then calculated phonon frequencies for every point in this dense grid. Lorentzian with at least 50 meV broadening was used to replace the delta function.…”

Assessment of empirical interatomic potential to predict thermal conductivity in ThO2 and UO2

“…The branch specific thermal conductivity is calculated considering all sampling points in the Brillouin zone. This is achieved by projecting the rotated eigenvectors for a general wave vector q (rotation in accordance with the relation between q and q ref (→ 0)) to the branch eigenvectors for q ref near the Γ point, and then applying weighting factors to the basic phonon branches near the Γ point (see reference [35] for theoretical formulations). To ease annotation, results obtained using IFCs from DFT calculations will be denoted DFT-FC and results using IFCs from the CRG potential will be denoted CRG-FC.…”