1ST-PRINCIPLES SIMULATIONS OF INTRINSIC COLLISION CASCADES OF 23-EV AMU SI AND 5-EV AMU TI ATOMS IN SINGLE-CRYSTAL SI AND TI

The slowing-down process of Ti atoms in crystalline Ti and Si atoms in crystalline Si is studied using the molecular-dynamics method. Based on an experimental technique available for studies of the slowing-down process of atoms at ultralow velocities in bulk matter, the initial r ecoil energy was 261 eV for Ti and 677 eV for Si atoms. The values cor respond to the energies imparted after the thermal neutron capture by primary gamma rays. The effect of the crystalline structure on the slo wing-down process is studied by calculating the energy distribution of the Doppler-shifted secondary gamma rays emitted by the recoiling nuc lei. The dependence of the distribution on the interatomic potential u sed in the simulations is also investigated.