New local model for electronic energy loss and its application to computer simulations of channeling

We used the average of the Thomas-Fermi (TF) electron distribution instead of that of Hartree-Fock (HF) electron distribution as the screening length of an isolated atom. Based on the Firsov theory, we proposed a new Firsov formula of the electronic energy loss which has a simple form ΔE_e(E, b) ∞ S_e(E) exp(γb)/(1 + βb)⁶, where S_e(E) is the electronic stopping cross section, b = p/a, p and a are the impact parameter and the screening length, respectively, and β and γ are the fitting parameters. Using the present screening lengths with the shell effect and the new Firsov formula, the depth distributions of channeling were simulated by the ACOCT code for 20 keV B⁺ ions impinging along the [1 1 0] channel direction of silicon (1 1 0) surface. The ACOCT depth profiles of channeling using the new Firsov (solid) local model for the AMLJ potential are in good agreement with the experimental ones.