Dynamic stability and magnetism of David star charge density waves in transition metal dichalcogenide systems

Monolayer group V transition metal dichalcogenides in their 1T phase have recently emerged as a platform the investigate rich phases of matter resulting from strong electron correlations. The magnetism of these systems interplays with different ordered phases, such as charge density waves (CDW). In particular, the so-called David star CDW phase (with a √13×√13 reconstruction) that might arise in these systems leads to the emergence of a spin 1/2 per David star, which has been discussed in the framework of spin liquids. In this talk, we present ab initio calculations based on the density functional theory of different V-, Nb-, and Ta-based chalcogenides. We study the band structure, density of states, and phonon spectra of various of these compounds in the √13×√13 cell, obtaining information about their electronic structure and the possible charge-density-wave q-vectors that may be responsible for the appearing instabilities, if these exist.