Search PubMed⌕ Search

Biomedical subjects

S Mazevet

Publications and source records attributed to S Mazevet.

8 recordsLinked to original sources
PubMed2006

Effect of intense laser irradiation on the lattice stability of semiconductors and metals.

The effect of intense ultrashort irradiation on interatomic forces, crystal stability, and possible melting transition of the underlying lattice is not completely elucidated. By using ab initio linear response to compute the phonon spectrum of gold, silicon, and aluminum, we found that silicon and gold behave in opposite ways when increasing radiation intensity: whereas a weakening of the silicon bond induces a lattice instability, gold undergoes a sharp increase of its melting temperature, while a significantly smaller effect is observed for aluminum for electronic temperatures up to 6 eV.

Journal Article↗
PubMed2005

Molecular-dynamics simulations of cold antihydrogen formation in strongly magnetized plasmas.

Employing a high-order symplectic integrator and an adaptive time-step algorithm, we perform molecular-dynamics simulations of antihydrogen formation, in a cold plasma confined by a strong magnetic field, over time scales of microseconds. Sufficient positron-antiproton recombination events occur to allow a statistical analysis for various properties of the formed antihydrogen atoms. Giant-dipole states are formed in the initial stage of recombination. In addition to neutral atoms, we also observe antihydrogen positive ions (H(+)), in which two positrons simultaneously bind to an antiproton.

Journal Article↗
PubMed2005

Ab-initio simulations of the optical properties of warm dense gold.

Using a combination of classical and ab-initio molecular dynamics simulations, we calculate the structure and the electrical conductivity of warm dense gold during the first picoseconds after a short-pulse laser illumination. We find that the ions remain in their initial fcc structure for several picoseconds, despite electron temperatures ranging from a few to several eV after the laser illumination. The electrical conductivities calculated under these nonequilibrium conditions and using the latter assumption are in remarkable agreement with recent measurements using a short-pulse laser interacting with gold thin films.

Journal Article↗
PubMed2005

Simulations of the optical properties of warm dense aluminum.

Using quantum molecular dynamics simulations, we show that the optical properties of aluminum change drastically along the nonmetal metal transition observed experimentally. As the density increases and the many-body effects become important, the optical response gradually evolves from the one characteristic of an atomic fluid to the one of a simple metal. We show that quantum molecular dynamics combined with the Kubo-Greenwood formulation naturally embodies the two limits and provides a powerful tool to calculate and benchmark the optical properties of various systems as they evolve into the warm dense matter regime.

Journal Article↗
PubMed2002

Evolution of ultracold neutral plasmas.

We present the first large-scale simulations of an ultracold neutral plasma, produced by photoionization of laser-cooled xenon atoms, from creation to initial expansion, using classical molecular-dynamics methods with open boundary conditions. We reproduce many of the experimental findings such as the trapping efficiency of electrons with increased ion number, a minimum electron temperature achieved on approach to the photoionization threshold, and recombination into Rydberg states of an anomalously low principal quantum number. In addition, many of these effects establish themselves very early in the plasma evolution ( similar ns) before the present experimental observations begin.

Journal Article↗
PubMed2001

Calculation of a deuterium double shock Hugoniot from ab initio simulations.

We calculate the equation of state of dense deuterium with two ab initio simulation techniques, path integral Monte Carlo and density functional theory molecular dynamics, in the density range of 0.67 < or = rho < or = 1.60 g cm(-3). We derive the double shock Hugoniot and compare with the recent laser-driven double shock wave experiments by Mostovych et al. [Phys. Rev. Lett. 85, 3870 (2000)]. We find excellent agreement between the two types of microscopic simulations, but a significant discrepancy with the laser-driven shock measurements.

Journal Article↗
PubMed2001

Magnetic and orbital dichroism in (e,2e) ionization of sodium.

We present the first measurement of (e,2e) ionization cross sections for a laser oriented atomic target by spin polarized electrons. Cross sections are presented as a function of target orientation and polarization direction of the incident electron beam. This study provides insight into mechanisms by which angular momentum is transferred from the valence electron to the two final-state continuum electrons in both singlet and triplet spin channels, by comparing measurement with distorted wave Born approximation and the dynamically screened three Coulomb wave calculations.

Journal Article↗