Electron-proton relaxation in hot-dense plasmas with a screened quantum statistical potential.

Modeling the nonequilibrium process between ions and electrons is of great importance in laboratory fusion ignition, laser-plasma interaction, and astrophysics. For hot and dense plasmas, theoretical descriptions of Coulomb collisions remain complicated due to quantum effect at short distances and screening effect at long distances. In this paper, we propose an analytical screened quantum statistical potential that takes into account both the short-range quantum diffraction effect and the long-range screening effect.

Trajectory-dependent threshold effects of proton stopping power in LiF nanosheets.

We conducted a study on the trajectory-dependent threshold effects of proton stopping power in LiF nanosheets using time-dependent density functional theory non-adiabatically coupled to the molecular dynamics. This study covered protons with initial velocities in the range of 0.1-1.

Effects of semicore electrons on stopping power in helium-irradiated aluminum nanosheets.

The stopping power of energetic He ions traversing an Al film is studied by combining the time-dependent density-functional theory method with molecular dynamics simulations. We investigated the dependence of the semicore electron excitation of the Al film on the projectile's trajectory and its charge state. Our results show that for the off-channeling trajectories the semicore electrons contribute significantly to the stopping power of the Al film as the He ion velocity exceeds 1.

Assessment of the electron-proton energy relaxation rates extracted from molecular dynamics simulations in weakly-coupled hydrogen plasmas.

Electron-proton energy relaxation rates are assessed using molecular dynamics (MD) simulations in weakly-coupled hydrogen plasmas. To this end, we use various approaches to extract the energy relaxation rate from MD-simulated temperatures, and we find that existing extracting approaches may yield results with a sizable discrepancy larger than the variance between analytical models, which is further verified by well-known case studies. Present results show that two of the extracting approaches can produce identical results, which is attributed to a proper treatment of relaxation evolution.

Stochastic radiative transfer in random media. II. Coupling of radiation to material.

We study the mechanism of the impact of random media on the stochastic radiation transport based on a one-dimensional (1D) planar model. To this end, we use a random sampling of mixtures combined with a deterministic solution of the time-dependent radiation transport equation coupled to a material temperature equation. Compared to purely absorbing cases [C.

Stochastic radiative transfer in random media: Pure absorbing cases.

We study stochastic radiation transport through random media in one dimension, in particular for pure absorbing cases. The statistical model to calculate the ensemble-averaged transmission for a binary random mixture is derived based on the cumulative probability density function (PDF) of optical depth, which is numerically simulated for both Markovian and non-Markovian mixtures by Monte Carlo calculations. We present systematic results about the influence of mixtures' stochasticity on the radiation transport.

Collision dynamics of proton with formaldehyde: fragmentation and ionization.

Using time-dependent density functional theory, applied to the valence electrons and coupled non-adiabatically to molecular dynamics of the ions, we study the ionization and fragmentation of formaldehyde in collision with a proton. Four different impact energies: 35 eV, 85 eV, 135 eV, and 300 eV are chosen in order to study the energy effect in the low energy region, and ten different incident orientations at 85 eV are considered for investigating the steric effect. Fragmentation ratios, single, double, and total electron ionization cross sections are calculated.

Theoretical study on collision dynamics of H(+) + CH4 at low energies.

In this work we make an investigation on collision dynamics of H(+) + CH4 at 30 eV by using time-dependent density functional theory coupled with molecular dynamics approach. All possible reactions are presented based on 9 incident orientations. The calculated fragment intensity is in nice agreement with experimental results.

The effects of electron transfer on the energy loss of slow He²⁺, C²⁺, and C⁴⁺ ions penetrating a graphene fragment.

Electronic energy loss in the collision processes of slow ions with a graphene fragment is investigated by combining ab initio time-dependent density functional theory calculations for electrons with molecular dynamics simulations for ions in real time and real space. We study the electronic energy loss of slow He²⁺, C²⁺, and C⁴⁺ ions penetrating the graphene fragment as a function of the ion velocity, and establish the velocity-proportional energy loss for low-charged ions down to 0.1 a.