(11/29/21) Through its research fellowship program, and since 2019 through the Walter Benjamin Program, the DFG supports junior scientists in their academic careers by funding an independent research project abroad and, since 2019, in Germany too. Many of these scholarships are taken up in the USA and Canada. This reflects the belief, prevalent in many disciplines and especially in the life sciences and natural sciences, that it is helpful for a career in research to have “been to America.” In a series of talks, we aim to give you an impression of the wide range of DFG funding recipients. In this edition, we look at who is behind funding number LA 4442.

DFG: Dr. Larsson, many thanks for taking the time to talk to us. From 2022 you’ll be leading a research group as an assistant professor of theoretical chemistry at the University of California (UC) in Merced. That probably isn’t something that your family would have imagined you doing when you were a child, right?

Henrik Larsson (HL): No, they would certainly have had different ideas, but let me start by saying a big thank you to the German Research Foundation (DFG) for giving me a research fellowship that allowed me to pursue my own projects for two years at the California Institute of Technology (Caltech) in Pasadena. To get back to your question: farmers and manual workers have hopes and dreams, too – but these don’t generally have to do with scientific research, molecular quantum dynamics or correlated electronic structure. My parents, and the vast majority of my relatives, work either in agriculture or the manual trades. Unfortunately, my father was unable to take over his father’s farm, so he first became a heavy goods driver and then an electronics technician. My family are still very much rooted in the practicalities of life – except perhaps my mother, who worked in a pharmacy.

DFG: How and when was your enthusiasm aroused for theoretical chemistry and the pursuit of an academic career? Were you something of an aloof high achiever during your school days?

HL: I certainly wasn’t aloof, nor was I a high flyer initially. At the end of primary school I even had problems getting a recommendation for higher secondary school. My handwriting was illegible – and has remained so to this day, by the way – and I probably had some difficulties expressing myself on paper, too. Fortunately, my mother intervened when I was recommended for lower secondary school and ensured I got a more demanding education. I then gradually moved to being top of the class – less out of ambition than out of curiosity for the subject matter. In fifth and sixth grade I was initially driven by the desire to become an inventor; a little later I set my sights on becoming a chemistry professor – though admittedly without having any idea of what that actually involved.

DFG: Can you remember the moment when you fell in love with chemistry?

HL: I think it was in ninth grade. Without much ado, the teacher placed two open bottles next to each other: one contained hydrochloric acid and the other ammonia, i.e. a strong base. What happened? A smoke column of ammonium chloride formed above the two bottles, in other words a solid was created from two liquids via their respective gas phase – without a Bunsen burner or any big bangs. What is more, two such opposing and dangerous substances turned into something that is an ingredient of liquorice – a harmless, edible foodstuff when eaten in moderation. That left a deep impression on me.

DFG: Did your other subjects then suffer after you discovered what you like best?

HL: No, I was actually very good at all subjects – perhaps not quite as good at Latin, art and sport, but even that didn’t traumatize me in the long term. I spend hours of my free time in the great outdoors hiking or jogging, I derive a lot of pleasure from art museums and I enjoy tossing around the odd Latin phrase here and there.

DFG: What about your interest in music?

HL: My grandfather was very musical, but I only inherited this from him in a passive sense. I don’t make music myself, but I do enjoy listening to it a lot and my tastes are quite wide-ranging – from Baroque to jazz and metal.

DFG: Did you ever get bored at school?

HL: No, not really. I could have skipped tenth grade, but actually I felt intellectually stretched enough even without taking on that extra challenge. Only at the very end, just before my school-leaving examination, did I finally get to the point where I couldn’t wait to tackle new questions at university – questions to which there might not even be any answers yet. But don’t get me wrong: I’m not a nerd in the classical, academic sense. Driving a tractor was as important to me at the age of 13 as trigonometry.

DFG: You then enrolled for a bachelor’s degree in chemistry. Farming or some other manual trade was never an option for you, despite having loved driving a tractor?

HL: No, but the reason wasn’t that I have two right hands as a left-hander or that I shied away from doing physically hard work. The challenges you face taking a university degree are different from those in the manual trades or agriculture. Have you ever seen how a schnitzel goes from the pigsty to the meat counter? As a farmer, that’s something you can’t avoid – and it’s one of the many reasons why I’ve become a vegetarian, as well as a chemist.

DFG: You then set out on the path of physical and theoretical chemistry having completed an excellent bachelor’s thesis. How did that come about and what do your father and mother get to hear when they ask what you do for a living?

HL: Even when I was in high school, I was fascinated by quantum mechanics and how it can be used to describe molecules. I got a taste of theoretical chemistry during a placement at university when I was in high school. I was fascinated by the fact that you can predict all the molecular properties such as color and state of aggregation purely based on simulations – without even producing the molecule in the laboratory. Chemistry is one of the few sciences where such things really are possible. Unlike physics, for example, we don’t have to deal with nebulous concepts such as dark energy that aren’t really understood yet. As far as my parents, my family and most of my friends are concerned, it’s been a long time since I had any great hopes of being understood in terms of the details of what I do for a living, but this in no way detracts from our mutual affection. It took a while for my parents to understand that I didn’t just copy out of books for my bachelor’s thesis but actually documented new research.

DFG: You grew up in Schleswig-Holstein, attending school and starting your studies at Kiel University. Since then you’ve expanded your radius considerably and have left your home turf. What was the pivotal factor here?

HL: I went to Sweden with the European Erasmus program while I was doing my master’s degree. As a former homebody, I can only say: everyone should go abroad once in a while, because once you’ve been away, you can understand and appreciate your own country a lot better. In my case, I spent seven months in Sweden – a formative period surrounded by other students from all over Europe. English was the lingua franca, but I picked up Swedish very quickly too, something that was hardly appreciated given my surname. I’m actually only 2/16 Swedish by birth and not even a particularly gifted linguist, which became uncomfortably clear when I attempted to learn Hebrew.

DFG: What drew you to Israel for a research stay?

HL: That was more of a coincidence and because only one of the ten or twelve papers I was handed for a research internship shortly before doing my master’s thesis was worded in a way I could understand. It was by David Tannor of the Weizmann Institute of Science in Rechovot, Israel. I went there for a stay during my doctoral studies. At the time, everything happened very quickly, which was quite a challenge given the double workload with the master’s thesis. It wasn’t until I was on the flight to Israel that I got time to look at a travel guide I’d purchased shortly beforehand.

DFG: In 2013 you spent time not only in Lund, Sweden, but also – even further away from Kiel – in Jülich, North Rhine-Westphalia, at the high-performance data center. How did you end up there?

HL: I got the chance to go as a guest student and I was given computing time for some modelling that I was working on at the time. Mind you, what I was doing back then wasn’t actually so complex that I couldn’t have done it on a somewhat smaller device than the Jülich supercomputer. Nonetheless, an environment like that is hugely inspiring, of course, and as a guest student I got to use an impressive machine – the JUQUEEN. The good lady was Europe’s fastest computer at the time.

DFG: You were at Caltech on a DFG research fellowship to conduct research into molecular quantum dynamics and electron structure theory. Were you happy there? What were the results of your work?

HL: The DFG-funded research stay was very productive and the publication it led to with me as sole author has attracted a very good response. I was very happy not just at the institute but in Pasadena in general. It’s very European as compared to nearby Los Angeles. Pasadena is nicknamed the “Rose City” for good reason and it’s the center of interest in the US at least once a year: when one of the numerous college football finals is played at the Rose Bowl Stadium, and when a million people from all over the country make their way to Pasadena at New Year to watch the Rose Parade.

DFG: After completing your research fellowship you decided to continue your career in the USA, i.e. you opted not to return to Germany. Weren’t the numerous offers to lead a research group in Germany attractive enough?

HL: At the 2019 meeting of the German Academic International Network (GAIN) in San Francisco, I did indeed seek advice on the Emmy Noether Program, but I didn’t go on to submit a proposal. My partner is from the US - she’s an astrophysicist, so the tiresome two-body problem arose for us. She ended up at the University of California (UC) in Merced and there happened to be a place at the same location for me as well. So here we are. I had offers from Germany, too, but they would have only been for me. In addition, the offer from Merced in terms of the resources for my position, as compared to that of a junior professorship in Germany, were better by a factor of about six: a better salary, less teaching, more computing capacity, a postdoc and two PhD students as core support, and the very realistic possibility of acquiring even more positions through the CAREER Awards of the National Science Foundation (NSF). That’s important to me, because I have enough ideas for no end of PhD students. In addition, the campus – which was founded by the University of California at Merced at least 20 years ago – is on the rise overall: it attracts lots of NSF grants and has now emerged from the murky triple digits of the international rankings, currently at 93, ahead of the UC in Santa Cruz.

DFG: Merced is located in California’s Central Valley and is probably not so well-known for its scenic attractions. How are you coping there after your stay in the Rose City?

HL: The Central Valley, i.e. the area around Merced, is actually a bit like Schleswig-Holstein: I look out of the window and see cows – not black and white Holstein cows, but still. And now I have the huge advantage of being able to get to Yosemite National Park in just one hour. That would only be possible from Pasadena by helicopter – and from Kiel by teleportation.

DFG: What’s the relationship between theorists and practitioners in chemistry?

HL: I’ve been able to gain experience with both theory and practice, and I even consider myself to be quite proficient when it comes to practical experimentation, but at some point I opted for theory because you can’t do both at the same time. I’m now in a position to be able to plausibly describe practical processes for you using the Schrödinger equation – in some cases much more precisely than you could measure in an experiment.

DFG: When it comes to Schrödinger, non-experts are happy to imagine a human being with the first name of Erwin and possibly also a cat that is simultaneously both alive and dead. You mentioned Monte Carlo integration in your funding proposal. What is that all about and does it have anything to do with the Monaco district of the same name?

HL (laughs): Yes, the technique is indeed named after the big casino is in Monaco. When you stand at a roulette table there, you can’t know which of the 37 compartments the ball will roll into next time. But you can predict with a very high probability that a very large number of roulette plays will include your chosen number between 1 and 36. This is also used for problems that are very difficult to solve analytically outside of casinos – it’s called the Monte Carlo simulation, Monte Carlo optimization or Monte Carlo integration. In fact that was exactly the part of my DFG research project that didn’t work out so well. I kept it to myself – probably like anyone who has come to a dead end at this point. It’s actually a shame that failures don’t get publicized; you learn just as much from failure as you do from success. In fact, I already have some ideas as to how I might put the Monte Carlo integration to promising use elsewhere.

DFG: In chemistry, is it the theorists who spur on the experimenters, or is it the other way round?

HL: Theorists drive each other and experimenters drive the theory. But it’s a matter of give and take in terms of intellectual stimulation. On a small scale, you can go quite a long way with theory, but as soon as you get to more complex molecules – especially in the macro range – you have to go back to the lab and get cooking.

DFG: Particular attention is now being paid to attracting more women to the natural sciences. What’s your impression of the gender ratio in chemistry?

HL: Gender balance – i.e. a roughly 50/50 split – is something we should actually already be able to observe in chemistry undergraduate studies in Germany, as well as at the academies and workshops on quantum chemistry. But there are still far too few women in the higher spheres of the profession, especially in Germany. Things are definitely better here in the US.

DFG: When it comes to theoretical chemistry, the cliché of Dr. Sheldon Lee Cooper – one of the main characters of the series “The Big Bang Theory” – is never far away. Do you collect notes on the fridge, too?

HL: Yes, I do collect notes – not on the fridge, but next to the bed, in case I wake up and have a brilliant idea that might otherwise get lost in the next deep sleep phase. Sometimes I have good ideas in the shower, too. But I haven’t got any waterproof writing paper yet. That might be an idea.

DFG: What are your notes about right now?

HL: My work is currently focused on learning to understand complex quantum systems. For example, there are iron-sulphur complexes that are of outstanding importance for enzymes in biology, in the synthesis of nitrogen. Nature does this much better than the Haber-Bosch process – but we’re more familiar with the latter. If we could use quantum mechanics to reproduce what nature can do without someone who has the insight of Fritz Haber or Carl Bosch looking over our shoulder, we would probably move forward by a quantum leap.

DFG: That might be difficult for a non-expert to understand. Do you have a simpler example by any chance?

HL: Even seemingly straightforward things like water are not yet understood in terms of quantum mechanics. According to the Isaac Newton’s models, water should actually have a pH of 8.5. But that would be too alkaline to shower in, even for Newton. The actual value measured is a pH of 7, but as yet we’re unable to derive this value quantum-mechanically. There’s no direct application for this – except perhaps that you’d have less to worry about quantum-theoretically as regards your skin’s acid layer when taking a shower.

DFG: The more complex the question, the smaller the group of people you can discuss it with. Doesn’t that make you a bit lonely in the long run? Or, to put it another way, how big is the community you are still able to profitably exchange ideas with?

HL: Researchers investigate new things! Of course it might get lonely from time to time, but you’re not right at the cutting edge on a round-the-clock basis, or at least you shouldn’t be. There are maybe anything between five and fifty people around the world who are directly involved in my field of research, depending on how narrow the focus is. But I have the good fortune to work between disciplinary boundaries – between communities that don’t actually talk directly to each other. This interdisciplinary approach expands my research community, but it’s also very desirable and beneficial in general. I experienced this at the summer academies organized by the Studienstiftung des Deutschen Volkes, which were always very profitable for me. The methods I’m working on are also being put to productive use in other scientific fields, such as image processing. My partner works in the field of dark matter research and I firmly believe that theoretical chemistry is able to help there. Modelling techniques derived from physics end up being used in the social sciences, too.

DFG: What does your typical work day look like? You probably don’t go straight to the lab at 6 o’clock in the morning, right?

HL: No, I don’t go to a lab – nor do I do anything at 6 o’clock in the morning. I’m a theorist and I hate being tired. Half past eight is the earliest I get up, and then it takes me a few hours more to wake up completely. Tea, coffee and trying to understand what my colleagues are doing are helpful when it comes to getting me fully awake. So I read papers. My own performance peaks between 3 o’clock and 6 or 7 o’clock in the evening or later. You can’t really be academically productive for more than four hours a day anyway, but fortunately your job consists of other activities that don’t require your entire brain – such as administrative tasks – and you can fill the rest of the working day with these.

DFG: What other methods do you use besides exchanging ideas with colleagues to come up with new ideas for your work?

HL: Ideas come to me when I’m running or hiking, for example, or when I’m doing applied physics/chemistry in the kitchen at home, such as cooking. I love cooking with my partner: as in research, success in cooking is about striking the right balance between technique and creativity. Everyone’s capable of that – you should practice, and of course enjoy the result afterwards.

DFG: Scientists are sometimes said to have a distinctive sense of humor. What makes you laugh?

HL: What makes me laugh? Pictures by Paul Klee, for example: I believe he had a very enigmatic sense of humor – even more enigmatic than the titles of some of his works. Are you familiar with his 1903 etching Two Men Meet, Each Believing the Other to Be of Higher Rank? I find this kind of thing funny, as well as literature by Jonas Jonasson, best known in Germany for his novel The Hundred-Year-Old Man Who Climbed Out the Window and Disappeared. Mind you, his humor is one or two orders of magnitude more eccentric than Paul Klee’s.

DFG: One final question. You mentioned the fact that not every research project bears the desired fruit. How would you rate the balance between joy and frustration in your work?

HL: The balance between frustration and joy? Well, the further you move away from the mainstream of thought, the more out of kilter it gets. In the field of theoretical chemistry or theoretical physics, I would say something like 10 to 90 – in other words there’s a lot more frustration than joy. But frustration might not be the right word to describe when something’s a hard nut to crack. It is a great pleasure when colleagues pick up on your work, however. This makes up for a lot of tedious hours.

DFG: In that case, we hope this conversation won’t fall into the “tedious hours” category. Thank you for this informative and entertaining interview, and we wish you all the very best in pursuing both your professional goals and your personal dreams.