Molecular dynamics simulation of radiation damage in bcc tungsten

Molecular dynamics simulations of collision cascades in pure tungsten are performed to assess the primary damage due to irradiation. For short-range interaction the universal potential is used [J.F. Ziegler, J.P. Biersack, U. Littmark, The Stopping and Range of Ions in Solids, Pergamon Press, 1985, p. 41], while for long-range interaction, three different embedded atom method potentials [M.W. Finnis, J.E. Sinclair, Phil. Mag. A 50 (1984) 45; G.J. Ackland, R. Thetford, Phil. Mag. A 56 (1987) 15; P.M. Derlet, D. Nguyen-Manh, S.L. Dudarev, Phys. Rev. B 76 (2007) 054107] are used, namely, Finnis–Sinclair, Ackland–Thetford and Derlet–Nguyen–Manh–Dudarev, the latter providing a more accurate formation energy for the 〈1 1 0〉 interstitial. The short-range and long-range potentials are smoothly connected. A new approach improving the reliability of such potential fits at short distances is presented. These potentials are then evaluated on the basis of displacement threshold, point defect formation and migration energies, thermal expansion and temperature of melting. Differences in the damage resulting from collision cascades are discussed.