Validate energy accounting for dynamically screened polar phonons

Determine whether, in two-dimensional semiconductors with dynamical free-carrier screening, the energy required to create a phonon should include the energy to create the electron–hole pair excitations that dress the phonon, and clarify the consequences of this choice for the coupled electron–excitation Boltzmann transport framework.

Background

The paper shows that in 2D materials the spectral shape of polar phonons deviates from a simple Lorentzian because of strong interference with electron–hole pair excitations. This complicates the definition of phonon excitations and their dissipation via anharmonicity, which is needed to obtain finite transport coefficients in the absence of Umklapp processes.

To proceed, the authors assume that the energy cost of creating a polar phonon includes the energy to create the electron–hole pairs that dress it when screening is treated dynamically, but they acknowledge that the validity of this assumption must be established in future work.