By combining DFT-based computational analysis and symmetry constraints in terms of group-subgroup relations, we analysed the formation of the native crystalline structure of loellingite FeAs2. We showed that the ground state of the material exhibits the ordered patterns of the electronic localization which are mainly associated with iron 3dx2−y2 orbitals and can be characterized in terms of nematic-like ordering. The ordering is the result of the close interplay of the lattice and the electron degrees of freedom. In a structural aspect, it pursues an energy quest to select the orthorhombic crystal lattice attributed to the Pnnm space group. In a charge aspect, the ordering is connected with the valence charge density redistribution that not only provides a high electronic polarizability but also gives rise to an extra-large magnitude of the negative component of the dynamical p-d charge transfer.
@article{arxiv.1603.02958,
title = {FeAs$_2$ formation and electronic nematic ordering: Analysis in terms of structural transformations},
author = {A. Pishtshev and P. Rubin},
journal= {arXiv preprint arXiv:1603.02958},
year = {2016}
}