System-Bath Dynamics
Thema:
Identifying key degrees of freedom for a physical description of chemical reactions
Einordnung:
Understanding microscopic processes in many-body systems ranging from small gas phase molecules to large proteins in solution is one of the main goals in modern molecular physics. In many cases, a purely classical treatment via molecular dynamics (MD) is possible, which allows one to treat a vast number (~1,000,000 with modern computers) of degrees of freedom (DOFs) explicitly. Despite such impressive capabilities of MD methods, a reduction of complexity is very helpful when analysing physical properties. However, it turns out that finding the right set of DOFs being relevant for the physical effect under study can often be a difficult task. Thus, systematic approaches to detect relevant DOFs are highly appreciated.
Beschreibung:
An important step towards a reduced description is the separation of the relevant DOFs, termed 'system' from now on, from irrelevant ones in the equations of motion. This results in the so-called Generalised Langevin Equation (GLE) for the system's dynamics. In this equation, the action of these irrelevant DOFs on the system is reduced to fluctuating and dissipative forces of an implicit bath. Any explicit information on the bath is thus lost. However, in a recent study, it has been demonstrated that this information can be restored via elaborate time series analysis. Practically it implies that, once a set of DOFs is incomplete for a description of some physical effect, the missing DOFs hidden in the bath can be detected.
Within the scope of this project the student is introduced to the general concept of system-bath partitioning, the MD methods and the GLE. She/he is going to implement the GLE-based time-series analysis in order to test its practical applicability using various model systems. Given the success of the methodology, an application to, e.g., chemical reactions in a large realistic molecular system is foreseen. More technical education like using Linux, scripting, programming, scientific writing, etc. is provided as well.
Betreuer: Fabian Gottwald