Complex structure due to As bonding and interplay with electronic structure in superconducting BaNi2As2

BaNi2As2 is a superconductor chemically related to the Fe-based\nsuperconductors, with a complex and poorly understood structural phase\ntransition. We show based on first principles calculations that in fact there\nare two distinct competing structures. These structures are very different from\nelectronic, transport and bonding points of view but are close in energy. These\narise due to complex As bonding patterns and drive distortions of the Ni\nlayers. This is supported by photoemission experiments. This leads to an\ninterplay of electronic and structural behavior including induced anisotropic\nof the electronic transport. The competition between these distortions is\nassociated with the complex behavior observed in BaNi2As2 samples.\n