Dynamic screening of an ion in a degenerate electron gas within the second-order Born approximation

作者：Nersisyan Hrachya B; Fernandez Varea Jose M^*; Arista Nestor R

来源：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms , 2015, 354: 167-171.

DOI：10.1016/j.nimb.2014.11.089

• Dynamic Friedel sum rule
• Born approximation
• Scattering theory
• Degenerate electron gas

The dynamic Friedel sum rule (FSR) is derived within the second-order Born (B2) approximation for an ion that moves in a fully degenerate electron gas and for an arbitrary spherically-symmetric electronion interaction potential. This results in an implicit equation for the dynamic B2 screening parameter which depends on the ion atomic number Z(1) unlike the first-order Born (B1) dynamic screening parameter reported earlier by some authors. Furthermore, for typical metallic densities our analytical results for the Yukawa and hydrogenic potentials are compared, for both positive and negative ions, to the exact screening parameters calculated self-consistently by imposing the exact dynamic FSR requirement to the scattering phase shifts. The B1 and B2 screening parameters agree excellently with the exact values at large velocities, while at moderate and low velocities the B1 approximation deviates from the exact solution whereas the B2 approximation still remains close to it. In addition, a Fade approximant to the Born series yields a further improvement of the perturbative approach, showing an excellent agreement on the whole velocity range in the case of antiprotons.

• 出版日期2015-7-1