Probing Potential-Energy Surfaces
The goal of the workshop is to discuss current issues and perspectives of PES in the underlying theoretical concepts and methods, as well as corresponding applications in the fields of heterogeneous catalysis, crystal growth or biophysics.
After successful meetings in 1994, 1999, and 2005, the workshop stays within the interdisciplinary tradition of the PPES series and aims at bringing together scientists with different backgrounds, e.g. in condensed matter physics, materials science, computational physics, chemistry, and industry. There will be experts of the field of total-energy calculations, scientists who develop or enhance methods, and those who apply the information gained by these techniques. Attendance is by invitation only, and the maximum number of participants is 40. There will be talks in the morning and in the evening. In between there will be a poster session, practical sessions and ample time for discussions on the topic of the workshop.
As detailed in the program and below, the workshop will feature ten sessions with scientific talks. The time slot for each lecture is 60 minutes of which at least 20 to 30 minutes are supposed to be dedicated to discussion.
Deliberately, the session on “Materials big data” was set to the very beginning of the workshop as the major future challenge of the field lies in the utilization of large-scale electronic-structure calculations and machine learning to solve the pressing questions of mankind like developing a carbon-neutral and energy efficient industry. PESs can be input to as well as output of machine learning approaches. Machine learning can also be used to reduce the dimensionality by predicting collective variable for both, sampling and plotting of a PES. We will discuss technical foundations of database infrastructure, the challenges to high-performance computing, ways to select physically meaningful descriptors, and different machine-learning algorithms.
“Heterogeneous catalysis” is a classical example for the usefulness of a PES point of view. The particular focus of this session will be the realistic treatment of catalysts by means of incorporating defects and the assessment of alternative reaction pathways by means of the topology of minima, transition states, and bifurcations.
“(Bio)molecules” feature a rich conformational landscape due to their flexible nature. In this session, we will discuss ways to sample their structure space as well as the pitfalls when it comes to a sufficiently accurate description of their energetics. Based on reduced PESs consisting of minima and selected barriers, ways toward free energy by means of differential equations or biased molecular dynamics (MD) will be discussed. Realistic treatment of MD, especially with regard to vibrational spectroscopy, requires the consideration of nuclear quantum effects. Ways to incorporate them with special MD thermostats or by means of ring-polymer path-integral MD will be discussed. Finally we will turn to the peculiarities of describing “water” as well.
In realistic materials, like the above-mentioned catalysts or also in “semiconductors and photovoltaics”, excited states and the coupling between electronic and nuclear motion ("electron-phonon coupling") play an important role, for example in electronic spectroscopy or in thermal transport. We will cover methods to incorporate such effects, in particular with a focus on “hybrid inorganic/organic materials”.
After having discussed all the current challenges and the apparent pitfalls, we will turn to the basic underlying concept of probing potential energy surface, namely the energy function in the two "basic conecpts" session. We start with discussing (i) ways to augment density-functional approximations for their lack of long-range van der Waals interactions and (ii) how far one can push meta-GGA functionals in terms of accuracy while still satisfying basic physical constraints. Finally, we are turning towards benchmark calculations – coupled cluster and quantum Monte Carlo - that are almost standard when it comes to molecules or clusters, but are just starting as a field of research when it comes to periodic systems like materials.
Finally, one session is dedicated to hot topics contributed by the workshop participants. Those contributions are selected from the abstracts submitted for posters.
Carsten Baldauf (Fritz-Haber-Institut der MPG) - Organiser
Matthias Scheffler (Fritz-Haber-Institut der Max-Planck-Gesellschaft) - Organiser