Thermodynamic stability of neutral Xe defects in diamond

Optically active defect centers in diamond are of considerable interest, and ab initio calculations have provided valuable insight into the physics of these systems. Candidate structures for the Xe center in diamond, for which little structural information is known, are modeled using density functional theory. The relative thermodynamic stabilities were calculated for two likely structural arrangements. The split-vacancy structure is found to be the most stable for all temperatures up to 1500 K. A vibrational analysis was also carried out, predicting Raman- and IR-active modes which may aid in distinguishing between center structures.