Figure 1

Friction coefficient of a homogeneous EG versus the projectile charge $Z_1$ (a)–(c) and the EG-density parameter $r_s$ (d), as obtained in the LDA from Eq. (12) (dashed chained curves) and from the sum of Eqs. (12, 14) (solid chained curves). (a) Solid circles, triangles, and diamonds are transmission measurements from Refs. 11, 12, 13 of the random SP of $\mathrm{C}$ for ions moving with velocities $v=0.41$, 0.83, and $0.25\mathrm{a.u.}$, respectively. (b) Solid circles and triangles are transmission measurements from Refs. 11, 12 of the random SP of $\mathrm{Al}$ for projectiles moving with velocities $v=0.41$ and $0.83\mathrm{a.u.}$, respectively. Solid squares (stars in the inset) are the measured SP of $\mathrm{Al}$ of Ref. 14 (Ref. 15) for slow ions $\left(v=0.5\mathrm{a.u.}\right)$ moving at a distance of $1.0\left(1.2\right)\mathrm{a.u.}$ from the last atomic row at the surface. (c) Solid squares are the measurements of Ref. 16 of the SP of $\mathrm{Au}$ for slow ions $\left(v=0.68\mathrm{a.u.}\right)$ channeled along the (110) direction. These measurements are compared to EG calculations with $r_s=2$. The dotted line is the calculation of Ref. 6 with dynamical xc effects included in the framework of linear-response theory.Reuse & Permissions