Simulations

Molecular Dynamics simulations are among the first techniques that was tested by numerical physicists, going back to the 40s and 50s. One of the first problems and discussions in the field of Molecular Simulations is the question of Can particles freeze in a purely repulsive, hard-sphere particles? Theories suggest this should be the case, but this question is obviously impossible to investigate experimentally, as Van der Waals forces will always be present in our systems. 

Berni Alder went on to perform these simulations together with Wainwright and the often forgotten Mary Ann Mansigh, and found positive results. These were presented at a conference, where a committee of world-famous physicists (including Nobel Prize winners) met and discussed whether these simulations provided sufficient evidence. Their conclusion was that computer simulations could not be trusted, but luckily, science does not care who you are. We now know they were wrong, and proves the utility of computer experiments: Remove complexity and uncertainties we encounter in the real world.

In our group, we do molecular simulations when it is needed. In particular, we have studied DNA-coated colloids and block co-polymers.

Our group is also doing Lattice Boltzmann simulations, which is a numerical solver based on the Boltzmann equation. This ignores the molecular positions themselves, with the advantage of handling the hydrodynamic equations of motion. This is one of the most popular methods for studying systems where both hydrodynamic interactions and thermal fluctuations are important, which we frequently find in soft matter physics.

In addition we are working on Multiple Particle Collision dynamics simulations, which are used for similar challenges in fluctuating hydrodynamics. In particular, we utilize these techniques to study the flow fields caused by thermophoresis.