Iowa Stateupdate

Rupa Dumpala, Joaquin Peralta, Scott Broderick

Simulations / DFT setup

• Initial configuration and settings for Si pseudopotential.o Choosing Ultrasoft / Norm conserved / othero Defining cutoff for Sio more than 23 pseudopotentials available in QE.

• Initial configuration and settings for O pseudopotentialo more than 26 available in QE.o Choose settings like the Si case.

• Looking for preliminary works in H and H2O.

Simulations / DFT setup

Methodology

• Carr Parrinello vs Bon Oppenheimer MD, in QE.o Updating background before making choice.o Time step and final simulation time

required about 5ps

• Preparing the Si-9 / O (after that, if it works well, simulate H and H2O too).

Si surface simulated using QE, the number of atoms was around 100. The time comparatives do not compare because the electric field was incorporated into this simulation. Without an electric field the simulation is considerably faster.

Interfaces study

use of algorithm and classical molecular dynamics to improve the reconstruction process from Atom Probe Tomography.

Analysis and study of specific interfaces by means of DFT. This example show a grain boundary and the associated charge density of the sample. The goal it is study the variation of this charge density around the interfacial zone in the presence of an electric field. The presence of high electric field is one of the operational characteristics of the APT.

Experimental Data Format