CM
In the literature: contested
Is the kagome charge-density wave electronic or phonon driven
In plain words
The charge order could arise from electrons near special points of the band structure interacting with each other, or from coupling to lattice vibrations that soften.
Precise statement
Determine whether the charge-density wave of AV3Sb5 is driven by electronic instabilities of the van Hove singularities at M (nesting and interactions) or by momentum-dependent electron-phonon coupling with a soft breathing phonon. An answer is inelastic x-ray measurements of phonon softening plus momentum-resolved electron-phonon coupling compared with the electronic susceptibility.
What would settle it
Inelastic x-ray scattering of the phonon dispersion versus temperature combined with first-principles electron-phonon and electronic susceptibility calculations.