The purpose of this project is to investigate (i) the strength of polymer interfaces and (ii) the impact of impurities on tungsten grain boundary strength. The former project is performed in collaboration with Tetra Pak.
For (i) we will use quantum mechanical (DFT, using quantum espresso and VASP) and classical molecular dynamics (MD, using LAMMPS) modelling to invetigate the bond strength between acetic acids or polyethylene and aluminium oxide films. To this end we will utilize the newly established vdW-cx exchange-correlation functional (developed by Per Hyldgaard et al.) and the reaxFF forcefield for classical modelling. The DFT modelling will be used to investigate the adsorption of individual chains/acid groups onto the surface. We will use classical MD to investigate the adhesion between amorphous polymers and aluminium oxide substrate for different multiaxial deformation modes. The slow strain rate combined with utilization of numerically expensive all-atom reaxFF force fields require large paralellization on multiple (up to 128) cores for about one week per simulation on tetralith. We estimate the need of about 100 000 core-hours per month over a year for this effort at the tetralith system.
For the tungsten grain boundary modelling we will use both DFT and classical atomistic modelling. Typically we intend to investigate how impurities affect the cohesive strength of grain boundaries. This effort requires the modelling of slip and brittle mechanisms for large supercells. To this end we will use the Kebnekaise system. A typical job would require up to about 112 cores. In total, we estimate the monthly use to 80 000 core hours per month on Kebnekaise.
The group will expand with one new PhD student in the autumn of 2019. THus, we kindly ask for more resources this year.