Computational exploration of Peierls instabilities in 1-dimensional chains through DFT

In the prototypical Peierls transition system, a half-filled 1-dimensional chain of hydrogen atoms, the metallic configuration in which all nuclei are equally distant has been shown to be unstable to ionic displacements, leading to an insulating, dimerized ground state composed of H2 pairs. Predicting Peierls transitions in systems is of great interest due to they emerge as a consequence of the SSH model of electron-phonon coupling and due to their association with charge density waves . In this talk, we focus on the ability of predicting the presence of such instabilities purely through Density Functional Theory (DFT) calculations. DFT results directly indicative of Peierls instabilities, such as pronounced Kohn anomalies in the phonon spectra and potential energy surfaces, are presented for a selection of systems (H, C, Na). Furthermore, the influence of the electron filling level on the geometry of the ground state unit cell is explored; a trimerized structure is found to be energetically favorable at third-filling.