Including the effects of electronic stopping and electron–ion interactions in radiation damage simulations

Abstract

Radiation damage is traditionally modelled using cascade simulations, and the effect of inelastic scattering by electrons, if included, is introduced via a friction term in the equation of motion. We have developed a model in which the molecular dynamics simulation is coupled to a model for the electronic energy, which evolves via the heat diffusion equation. Energy lost by the atoms, due electronic stopping or electron-ion interactions, is input to the electronic system via a source term in the diffusion equation. Energy is fed back to the atomic system from the hot electrons by means of a Langevin thermostat, which depends on the local electronic temperature. Results of the model are presented for 10 keV cascades in Fe.

Ion and electron irradiation-induced effects in nanostructured materials

“…[240][241][242][243] Recently also twotemperature models have been implemented to examine EPC in cascades. 244 However, the problem is not symmetric with laser ablation and swift heavy ions since in cascades the ionic system is heated first and the electronic one later. Moreover, the ionic system is already distorted by nuclear collisions when it starts transferring energy to electrons, and hence EPC models derived for perfect lattices may not be appropriate.…”

The treatment of electronic excitations in atomistic models of radiation damage in metals

“…A demonstration of how simple scaling relationships (b) can capture much of the behaviour of the electronic stopping power (a) for a variety of projectile and target combinations. The scaling of stopping power by 1/Z 2 1 is informed by the pre-factor in the fast particle stopping theories (6), (8) and (18) and the normalisation of the particle velocity by 1/Z 2/3 1 is suggested by the Thomas-Fermi scaling of electronic velocities. (Data are from the database of Paul [25].…”

“…Such two temperature models have been widely explored and form part of some of the atomistic simulation schemes [8,9,77,78,79,80] to be discussed in section 5.…”

“…In the opposite case of T e > T i , a negative β i will provide an accelerating force. In a practical simulation scheme, T i can be replaced by an average T I over some coarse-grained cell of the ionic system [8].…”

Physics of intense, high energy radiation effects.

“…The basis for our work has been described in papers focused on ionization effects in metals [19,20]. In this approach, the ionization portion of the energy loss of a particle heats the electronic subsystem.…”