Development of an interatomic potential for the simulation of phase transformations in zirconium

Abstract

In recent years, some 30 studies have been published on the molecular dynamics (MD) of zirconium, primarily of its twinning deformation and response to radiation damage. Its low thermal neutron absorption makes it uniquely suited for the latter application. Surprisingly, currently used interatomic potentials do not encapsulate the unique properties of Zr, namely its high stacking-fault energy, anomolous self-diffusion, melting and phase transformation under temperature and pressure (or alloying). Ab initio calculations have shown deficiencies in the description of point defects, both vacancies and interstitials, using existing interatomic potentials, deficiencies that can now be rectified by refitting. Here, we show the calculation of phase transitions self-consistently and present a potential for Zr that correctly reproduces the energetics of our extended database of ab initio configurations and high-temperature phase transitions. The potential has an analytic many-body form, making it suitable for existing large-scale MD codes. We also present a best-fit potential for the hcp structure and its defects.

Acknowledgements

The authors thank R. C. Pasianot, D. J. Sordelet, M. J. Kramer, J. R. Morris and B. S. Bokstein for helpful discussions. The Ames Laboratory is operated by Iowa State University under the US Department of Energy (DOE) Contract No. W-7405-ENG-82. MIM was supported by the Office of Basic Energy Sciences of US DOE, GJA by EPSRC under grant S81186 and the EU under the PERFECT grant.