eFF, a method to simulate large scale excited electron dynamics

Dynamics simulations

In the videos below, electrons are shown as spheres of varying size. Spin is indicated by color: up spins are red, down spins are blue, and paired pairs are grey.

Warm dense hydrogen

These videos illustrate the transition from molecules to separated atoms that occurs when dense hydrogen (0.34 g/cc) is heated from 9,000 K to 30,000 K. As the temperature increases, the average electron size increases as well, which contributes to the increasing pressure.

Auger process in diamondoids

These videos show how the Auger process leads to ejection of electrons and carbon fragments in adamantane and a diamond nanoparticle over 100 fs. In adamantane, the process causes widespread fragmentation, while in the nanoparticle much of the energy is dissipated into the bulk, and only a CH species is ejected.

Diamond etching by hydrogen plasma

These videos show a diamond nanoparticle and a diamond surface in contact with various excited forms of hydrogen. In the first two cases, heated hydrogen molecules (3,400 K) and atoms (22,000 K) are used, compressed with spherical boundary conditions; in the last case a hydrogen plasma with periodic boundaries is used.

B₁₂ + hydrogen (eFF2)

These videos show hydrogen impacting on an icosahedral cluster of boron atoms (which is a local minimum structure). At low speeds, the hydrogen bounces off elastically, but at higher speeds the collision excites electrons. At the highest speed, fragmentation of the hydrogen occurs, a proton penetrates to the center of the cluster, and an electron is ejected.

Uniform electron gas (eFF3)

These videos show the fluxional nature of the uniform electron gas in eFF, simulated over 0.5 ps at different temperatures. The electron motions at low temperature are smaller and more strongly correlated.