Numerical study of defects in protactinium carbide

Abstract

Actinide carbides, like ThC and UC, have been widely studied in recent years, on the contrary, protactinium carbide has merited less attention. One issue of PaC that has not been approached, neither experimentally nor theoretically is the formation of defects and the incorporation of impurities. Therefore, we will focus on these topics through a numerically study. To accomplish this, we calculate formation energies of vacancy, tetrahedral interstitial, Frenkel pair, Schottky and antisite defects. We find that C vacancies are the energetically preferred defect. We analyze density of states, charge densities and distortion of lattices with these kind of defects. We also study the effect of incorporation of oxygen and helium in vacancy and interstitial defects. In view of the lack of both theoretical and experimental results in PaC, we compared with UC and ThC. As a measure of the efficacy of the protactinium pseudopotential, which we generate, we calculate structural parameters and phonon spectrum.