Nonlinear electronic stopping of negatively charged particles in liquid water

We present real-time time-dependent density-functional-theory calculations of the electronic stopping power for negative and positive projectiles (electrons, protons, antiprotons, and muons) moving through liquid water. After correction for finite mass effects, the nonlinear stopping power obtained in this paper is significantly different from the previously known results from semiempirical calculations based on the dielectric response formalism. Linear-nonlinear discrepancies are found both in the maximum value of the stopping power and the Bragg peak's position. Our results indicate the importance of the nonlinear description of electronic processes, particularly, for electron projectiles, which are modeled here as classical point charges. Our findings also confirm the expectation that the quantum nature of the electron projectile should substantially influence the stopping power around the Bragg peak and below.

Automated summary

We conducted real-time time-dependent density-functional-theory calculations on the electronic stopping power of negative and positive projectiles moving through liquid water, including electrons, protons, antiprotons, and muons. Our results, after accounting for finite mass effects, show significant differences compared to previously known semiempirical calculations using the dielectric response formalism. We found discrepancies between the linear and nonlinear stopping power, both in terms of the maximum value and the position of the Bragg peak. Our findings highlight the importance of accounting for nonlinearity in electronic processes, particularly for electron projectiles modeled as classical point charges, and confirm the expected substantial influence of the quantum nature of electron projectiles on stopping power around and below the Bragg peak.