State of the art ab initio total-energy calculations are used to investigate the properties of a large number of antisite and antistructure defects in c-${\mathrm{As}}_2$${\mathrm{Se}}_3$. Calculations of their formation energies are made, and an examination of their electronic states and relaxed geometries is performed. Surprisingly it is found that a select set of the antistructures undergoes bond-switching reactions that give rise to a new peculiar class of defects. These bond-switched antistructure defects are found to have lower formation energies than any of the antistructures. One of these is of particular interest as it forms a bridging bond between the layers of c-${\mathrm{As}}_2$${\mathrm{Se}}_3$. This cross-linking defect (CLD) is examined in more detail. It is found that the associated bond-switching reaction proceeds with small or no barrier for most charge states. This is surprising as the atomic movements associated with the formation of the CLD are quite large.

• Received 26 September 1988

DOI:https://doi.org/10.1103/PhysRevB.39.6017