Charged particle energy loss to electron gas

The contribution of the conduction electrons to the stopping power (– d E /d x ) of fast charged particles in a crystal has been calculated using different forms of the dielectric function. The various approximate forms of dielectic functions used are: 1. random phase approximation (RPA), 2. Hubbard approximation (both, screened and unscreened), 3. Kleinman approximation, and 4. the dielectric function obtained by variational calculation of Langreth. The intermediate velocity range for the incident particles, namely 2 V F < V <10 V F was investigated and it has been found that in this region the stopping power varies inversely to the particle velocity. Moreover the velocity dependence is found to be insensitive to the form of the dielectric function used in the calculation.