Quantitative electronic stopping power from localized basis set
Résumé
The electronic stopping power of a swift ion in matter can be obtained from ab initio calculations within time-dependent density functional theory. Most implementations rely today on a plane-wave plus pseudopotential approach, but at the expense of very cumbersome calculations. We show here that localized orbitals, especially with Gaussian-type orbitals, are a valuable alternative. These calculations can yield electronic stopping powers in quantitative agreement with the plane-wave results while maintaining a computational burden that is relatively low. These positive results are possible only when using Gaussian basis sets that were specially designed for the stopping power calculations. With this tool, we investigate the discrepancy between ab initio calculations and experiment at large velocity, the effect of the exchange-correlation functional, and the role of core excitations in the total stopping power. We rule out the widespread centroid path approximation as soon as the core electrons are involved in the process.