RESEARCH - SIMULATIONS

Calculated change in charge distribution in an oligomer:fullerene pair

"Calculated change in charge distribution between g.s. and first to third excited states in an oligomer:fullerene pair. Electron density moves from red to blue regions. Degree of charge transfer and excitation energies are also indicated for each transition." Sheridan Few, Jenny Nelson

One nanosecond simulation of a cluster of one sulphuric acid and six water molecules

The movie shows a one nanosecond simulation of a cluster of one sulphuric acid and six water molecules. The Empirical Valence Bond (EVB) methodology was employed within a modified version of DL-POLY 4.0.3 such that proton transfer could occur within the system. If a hydrogen atom leaves the sulphuric acid species it is coloured blue making it is possible to follow its trajectory through the water network. Whilst in the water network the hydrogen atom is known as an excess proton. The grotthuss mechanism is observed in the simulation where the mobility of the excess proton is enhanced by its ability to eject one of the other two hydrogen atoms within the water molecule to which it is attached.

Credits: Jake Stinson: UCL, LCN, TYC, London;  Ian Ford: UCL, LCN, TYC, London;  Shawn Kathmann: Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.

Simulation of melting evolution of a 10nm gold nanofilm

Simulation of melting evolution of a 10nm gold nanofilm irradiated with an ultrafast laser pulse of 41mJ cm-2 fluence (25 ps). The structure dynamics quantitatively reproduces the experimental time-resolved electron diffraction measurements and hence this atomistic model is a faithful representations of the melting process occurring at a picosecond time-scale. Red colour represents atomic environments of low local centro-symmetry (i.e. molten) and blue represents crystalline environments (i.e. solid).

Credit: Szymon L. Daraszewicz1, Yvelin Giret1,2, Nobuyasu Naruse2, Yoshie Murooka2,
Jinfeng Yang2, Dorothy M. Duffy1, Alexander L. Shluger1, and Katsumi Tanimura2

1 Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London, United Kingdom
2 The Institute of Scientific and Industrial Research (ISIR), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan

Physical Review B, accepted.

Ferropericlase at 2000 K and 140 GPa

MPG animation of an ab initio molecular dynamics simulation of the earth material ferropericlase (Mg,Fe)O at a temperature of 4000 K and a pressure of 140 GPa.

Credit: Eero Holmstrom, UCL