Role of electrons in collision cascades in solids. I. Dissipative model

M Caro and A Tamm and AA Correa and A Caro, PHYSICAL REVIEW B, 99, 174301 (2019).

DOI: 10.1103/PhysRevB.99.174301

We present a detailed model for the nonadiabatic coupling between ions and electrons in energetic ion-solid interactions over a wide range of energies in concentrated solid-solution fcc alloys of the 3d transition metals Ni, Co, Fe, and Cr. The model is based on general statistical mechanical principles and results in a stochastic modification of the classical nuclei motion which is parameterized by the first-principles calculation of a dissipation function produced by explicit time- dependent electronic evolution. This model provides a full picture of an entire collision process, from the ballistic to the thermal phases of a cascade, giving a detailed description of the energy exchange between ions and electrons till their final thermalization, removing in this way some ad hoc assumptions used in the state-of-the-art atomistic two- temperature models. This work is separated in two papers; in the present Part I, we report on the ab initio methodology used to translate stopping power and electron-phonon interaction into a parameterized dissipation function; Part II, to be published, addresses the nonadiabatic ion dynamics using our modified Langevin dynamics Tamm et al. Phys. Rev. Lett. 120, 185501 (2018) applying the dissipation functions developed here to specific collision cascade events.

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