Latest update: 14 December 2025

Porthania building, City Center Campus, University of Helsinki

Address: Yliopistonkatu 3

The lectures will be held in lecture hall PIII. The nearest metro station is Helsingin yliopisto (University of Helsinki), which is next door to Porthania.

The organising committee consists of

• Susi Lehtola, University of Helsinki
• Dage Sundholm, University of Helsinki
• Stefan Taubert, University of Helsinki
• Theo Kurtén, University of Helsinki

Jacques Desmarais, University of Turin

• Lecture 1: Lattice summations for theoretical chemistry of solids
• Lecture 2: The relativistic effective core potential approximation
• Lecture 3: Spin-current density functional theory

Janus Juul Eriksen, Technical University of Denmark

• Lecture 1: A history of full configuration interaction theory
• Lecture 2: The recent renaissance of near-exact approximations
• Lecture 3: Many-body expanded full configuration interaction

Arno Förster, VU Amsterdam

• Lectures 1-3: Green's functions methods (mostly GW-BSE) in theory and practice

Christof Holzer, Karlsruhe Institute of Technology

• Lecture 1: A closer look on the behavior of DFT beyond the ground state
• Lecture 2: Designing density functional approximations for properties
• Lecture 3: Electronic structure methods and properties: a comprehensive guide

Ida-Marie Høyvik, Norwegian University of Science and Technology

• Lecture 1: Local orthogonal orbital spaces: possibilities and limitations
• Lecture 2: Molecules: electronically open or closed?
• Lecture 3: An electronic structure perspective on non-covalent bonding

Stanislav Komorovsky, Slovak Academy of Sciences

• Lecture 1: Introduction to Relativistic Effects in Quantum Chemistry
• Lecture 2: Spin-Orbit Effects, Part 1: Impact on EPR Parameter Calculations
• Lecture 3: Spin-Orbit Effects, Part 2: The Heavy Atom–Light Atom Effect in NMR and Its Correlation with Bond Length

Susi Lehtola, University of Helsinki

• Lecture 1: Discussion on reusable libraries in quantum chemistry

Roland Lindh, Uppsala University

• Lecture 1: Contemporary MCSCF and multi-state multi-configurational methods—state of the art
• Lecture 2: The future of multi-configurational wave function models—where do we go now?
• Lecture 3: The optimization problem in QC methods—the dawn of GPR methods

Contributed Talks

In addition to the lectures, three 25-minute contributed talks will be given at the winter school, followed by five minutes of discussion, each.

• Andy Jiang, Higher Order Pair Natural Orbital-Based Coupled-Cluster Methods
• Mateusz Witkowski, Correlation Energy Per Bond
• Maximilian Breitenbach, Development of a low-scaling multicomponent DFT algorithm

The School is free of charge for academic staff at any level: students, postdocs, as well professors are all welcome to attend the school.

The school is an in-person event, only. There will be no possibility for remote participation.

Please note that since the school is free of charge, we are unable to provide support for travel or accomodation costs. Please also note that we are unable to sponsor visas or provide invitation letters for the participants, since in the cases these are necessary, the visa process wouldn't even finish in time for the winter school.

Registration has closed.

Please prepare your poster in (at most) A0 size in portrait orientation, i.e., width 841 x height 1189 mm. The poster boards are designed for this orientation, and posters wider than this will not fit.

The main poster session will take place on Monday afternoon (5 pm to 7 pm). The posters can be up in the lobby of the Porthania building (Yliopistonkatu 3) until Wednesday afternoon. In the program, there is another poster session on Tuesday afternoon, which has no official arrangements, but you have time to freely discuss at the posters if you want.

Students who wish to have credits for the course, should write an essay on one of the School topics, and return it before 15 Feb 2026. You find a list of essay topics in the same folder as the Lecture Notes (above), as well as below.

The length of the essay is about 3 A4 pages when pictures are not counted. The essays will be returned using this form: Link. It is not allowed to use AI-tools to produce the text.

The course is valued at 3 ECTS.

The essay topics are:

1. Configuration interaction and optimizing techniques
2. Divide and conquer: As full CI as possible
3. The CASSCF, RASSCF and GASSCF levels of theory
4. Quantum chemistry methods for periodic systems
5. Optimization techniques of multiconfiguration SCF wave functions.
6. Calculating molecular properties at DFT levels of theory
7. Density functional theory levels of theory
8. Green's function theory in quantum chemistry
9. Calculating excited states using Green's function theory and Bethe-Salpeter equations
10. Many-body expanded FCI
11. Calculating the electronic structure of molecules at relativistic levels of theory
12. Multicomponent quantum chemistry methods
13. Machine learning and electronic structure calculations
14. Ab initio correlation calculations in localized orbitals
15. The origin of weak intermolecular interaction
16. Title of your own choice (it should be related to the theme of the Winter School)

• List of Hotels in Helsinki

• Arriving at the airport, you can take the public bus 600 or the train connection between the airport and the central railway station with ringrail trains I and P. You need an ABC zone ticket, which you can buy from a vending machine, an R-kioski -shop or with the HSL mobile phone app. You might consider buying a four-day ticket (see tip below).
• Information about tickets for public transport (HSL): Link to HSL pages . To move around in the city center area, you will need to buy a AB ticket. However, for the airport you need a ticket for zones ABC. A four-day ticket for the ABC zone will cost 30,00 €. You can also buy tickets with the mobile phone app "HSL".
• The HSL app, The Journey Planner for public transport, and Google Maps might be helpful. Wikipedia knows about public transport in Helsinki as well.
• A taxi from the airport to the city centre should be around 40–50 €. Note: Taxi prices are unregulated, so a ride can in principle cost anything. Best to ask the driver beforehand. This applies to all taxi rides, not only from/to the airport. Note that Uber is legal in Finland, and we recommend using it to avoid any unpleasant surprises. Bolt is also a recommended alternative. Some Finnish taxi companies also have their own apps, but they are not as easy to use as Uber or Bolt.
• Look at the latest weather reports before travelling as temperatures might drop below the freezing point for the Winter School week.

For the evenings, we have collected a list of places suitable for slightly larger groups. The ones in italics are also good for just a drink or three. See also the map of restaurants. The organizers recommend

• Cella - a traditional restaurant in the Kallio district
• Elite - a traditional culture and artist restaurant
• CoolHead - a craft brewery on the Viikki campus that also serves pizza; especially famous for their sour beers
• Fat Lizard - a craft brewery restaurant in downtown Helsinki
• Manala - the place for late night eats
• St Urho's Pub - a pub close to the parliament building that also serves food from Manala's kitchen
• Juttutupa - one of the oldest restaurants in Helsinki
• Kaisla - a bar in downtown Helsinki with one of the best beer selections
• Konstan Möljä - traditional Finnish buffet