One-dimensional excitonic ground states in phosphorene atomic chains

Abstract

One-dimensional phosphorene atomic chains are predicted to have excitonic ground states when an electric field is applied along the nanochain system. By using the configuration interaction approach beyond the conventional framework of independent multiexcitons, we reveal that the ground state of the atomic chain undergoes two successive transitions, first from purely electronic to excitonic and then to almost fully bi-excitonic with the increasing electric field. As the length of the nanochain increases, the transition fields at which the excitonic ground state emerges are found to gradually decrease and converge to 0.015 V/nm. Further analysis shows that clusters of high-lying states rapidly become localized around the left and right ends of the nanochain when the applied electric field increases. Such localization greatly enhances the correlations among the many-particle configurations, which are believed to result in firstly the excitonic then the bi-excitonic ground state being energetically more favorable.