Prof. Dr. Christian Ochsenfeld - LMU München
Briefly describe your current position, research focus, and role within MCQST.
I am a professor for theoretical chemistry focusing on the solution of the Schrödinger equation for the atomistic description of large molecular systems (the field of quantum chemistry). While the Schrödinger equation is exact in a non-relativistic sense for constructing atoms and molecules (as well as their solid-state aggregates) out of the positively charged nuclei and the electrons and it is simple to write down the exact wave function for any system, its solution is currently impossible for large systems and overcoming this challenge extremely difficult. Therefore, an entire hierarchy of approximate ab-initio methods is available for solving the Schrödinger equation allowing for systematically approaching the exact solution. The difficulty in approaching the exact solution is the strong, exponential increase of the computational effort with the number of atoms.
Here is the focus of my group: to develop fast methods with only linear scaling effort (instead of, e.g., N**6 depending on the approximation) that fully preserve the accuracy and the numerical control. This allows us to treat molecules of unprecedented system sizes.
A key in approximate solutions to the Schrödinger equation is electron correlation, where in particular so-called 'strong correlation effects' pose severe difficulties for large systems. Developing efficient solutions to this key aspect is central to my group, which also offers direct and interesting links to several other theory groups in MCQST working in the field of quantum many-body theory.
How does a typical workday look like for you and what were the biggest challenges?
During Corona times everything is somewhat different. Working from home (or any other place) as a theoretician is straightforward, since our working instruments are paper and pencil, laptops, and our local high-performance computer cluster. Besides research, of course, teaching and administrative as well as reviewing duties keep me busy and sometimes the email inbox is a nightmare, with zoom meetings round the clock...
However, the most challenging part in 2020 was and still is clearly home office with our son Christoph who just turned three in December. My wife (also a professor) and I have been oscillating between online lectures, online teaching, online meetings etc., and so did our son Christoph, who like us turned into a true zoom expert...