Title: Investigations of energy landscapes of chemical systems

Title: Investigations of energy landscapes of chemical systems
Speaker: (Prof. Dr.) J. Christian Schön, MPI for Solid State Research, Stuttgart, Germany
Abstract: Trying to understand the existence and dynamics of chemical compounds and the route to their synthesis, requires us to explore the space of possible configurations of the corresponding chemical system together with the potential energy hypersuface over this space, the so-called energy landscape. Every (metastable) compound in a given chemical system corresponds to a locally ergodic region on this landscape, and the probability flows on the landscape describe the natural (relaxation) dynamics of the system.[1] For small molecules, such an analysis is by now rather straightforward, but for crystalline systems or large molecules and clusters the task is still non-trivial.
In this talk, I will first present some fundamental concepts of energy landscapes and give a quick overview of the most common methods used to explore such landscapes. Subsequently, I will show a number of examples of energy landscapes of crystalline and amorphous solids where we have predicted the existence of new crystalline modifications[2] and investigated the aging process of amorphous materials[3]. Finally, some recent work on clusters[4] and molecules on surfaces will be discussed.
[1] J. C. Schön, M. Jansen: Prediction, determination and validation of phase diagrams via the global study of energy landscapes, International Journal of Materials Research, 100, (2009), 135-152

[2] M. Jansen, J. C. Schön: Structure prediction in solid-state chemistry as an approach to rational synthesis planning, in: Comprehensive Inorganic Chemistry II, Eds. J. Reedijk, K. Poeppelmeier, pp. 941-969 (Elsevier, Amsterdam, 2013)

[3] A. Hannemann, J. C. Schön, M. Jansen, P. Sibani: Nonequilibrium Dynamics in Amorphous Si₃B₃N₇, Journal of Physical Chemistry B, 109, (2005), 11770 - 11776

[4] R. Pacheco-Contreras, M. Dessens-Felix, D. J. Borbon-Gonzalez, L. Oliver Paz-Borbon, R. L. Johnston, J. C. Schön, A. Posada-Amarillas: Tetrahelix conformations and transformation pathways in Pt₁Pd₁₂ clusters, Journal of Physical Chemistry A, (2012), 116, 5235-5239