Trygve Helgaker

Professor - Theoretical chemistry
Image of Trygve Helgaker
Norwegian version of this page
Phone +47 22855428
Room V236
Visiting address Sem Sælands vei 26 0371 Oslo
Postal address Postboks 1033 0315 Oslo


Trygve Helgaker works in the area of molecular electronic-structure theory—in particular, on the development and application of methods for quantum-mechanical simulations of molecular systems. With the emergence of powerful computers and the development of sophisticated simulation models and techniques, quantum-chemical simulations have become an indispensable tool for modern chemical research. Such simulations can be performed either as a supplement to experimental work (e.g., for interpretation of experimental data) or as a replacement of experimental investigations (when these cannot be performed or are too expensive).

Even though modern quantum-chemical methods are nowadays successfully applied to a vast range of problems in research and industry, there are still many restrictions with respect to applicability and accuracy. Helgaker's research is directed towards the development of efficient computational methods for large molecular systems, containing hundreds of atoms. Helgaker is also working towards the development of more accurate and flexible quantum-chemical methods, to make studies on large systems as accurate as those on small and medium-sized systems. Two important areas of research are on the fundamentals of density-functional theory (DFT) and molecules in extreme environments such as ultrastrong magnetic fields.

Since the 1980s, Trygve Helgaker has developed the quantum-chemistry program system Dalton in cooperation with other researchers in Scandinavia. 


Trygve Helgaker (born 1953) received the degree of cand. scient. in chemistry (gas-phase electron diffraction) in 1980 and the degree of dr. philos. (theoretical  chemistry) in 1986, both at the University of Oslo. After postdoctoral positions at the Institute for Mathematics and its Applications (IMA), University of Minnesota in 1986–87 and at the Department of Chemistry, Aarhus University in 1987–89, Helgaker became an associate professor (førsteamanuensis) at the Department of Chemsitry, University of Oslo in 1989, where he became a full professor in 1993.

Helgaker was on sabbatical leave in the group of Prof. Nicholas Handy at the University of Cambridge in 1999–2000 and in the group of Prof. David Tozer at Durham University in 2006–07. In January 2003, Helgaker a was a guest professor at Laboratoire de Chimie Quantique, Université Louis Pasteur in Strasbourg and a guest professor at Laboratoire de Chimie Théoretique (LCT), Université Pierre et Marie Curie (UPMC) i Paris i november 2013. From 2013 to 2017, Helgaker was the director of the  Centre for Theoretical and Computational Chemistry (CTCC), a Centre of Excellence shared with UiT The Arctic University of Norway 2007–2017. During the academic year 2017–2018, he was the group leader of the project Molecules in Extreme Environments at the Centre for Advanced Study (CAS) at the Norwegian Academy for Science and Letters. Since  2017, he is the director of the Hylleraas Centre for Quantum Molecular Science, a Centre of Excellence shared with the UiT The Arctic University of Norway.

Helgaker studied Russian at University of Leningrad in 1974–75 and worked as an assistant for Prof. Geir Kjetsaa at the Department of Slavic and Baltic Studies, University of Oslo in1979 (6 months), on the project Written by Dostoevsky? He taught Russian syntax at the same Department spring 1980.


Trygve Helgaker has authored 343 publications with 24000 citations and H-index 74 on ISI Web of Science and 33000 citations and H-index 86 on GoogleScholar

With Poul Jørgensen and Jeppe Olsen from the Department of Chemistry, Aarhus University, Helgaker has published a 1000-page monograph Molecular Electronic-Structure Theory (Wiley, Chichster, 2000), which has been cited more than 3000 times.

Helgaker has translated Russian fiction to Norwegian: Leo Tolstoy, Om vold og kjærlighet (Solum, Oslo, 1977) and Boris Pilnyak, Armesjefens død, in Moderne russiske fortellere, ed. G. Kjetsaa (Aschehoug, Oslo, 1977).


Helgaker has given 116 lectures at international meetings and conferences, 86 guest lectures at departments and research institutions, and 283 lectures at international summer and winter schools in quantum chemistry. Many lectures can be downloaded here, which also contains a full list of all lectures.

Awards and honours

Meetings and workshops organized


Trygve Helgaker has most recently taught the course KJM2600 – Quantum chemistry and spectroscopy at the Department of Chemistry; slides for 2012 are available  here.

Sostrup Summer School: Quantum Chemistry and Molecular Properties

Together with Poul Jørgensen and Jeppe Olsen at Aarhus University, Helgaker organized biennially from 1990 to 2014 the Sostrup Summer School: Quantum Chemistry and Molecular Properties, see invitation from 2010 and information about previous summer schools here. Many of his lectures can be downloaded here. Textbook for the summer school is Molecular Electronic-Structure Theory (Wiley, Chichester, 2000), written by Helgaker, Jørgensen and Olsen.

Other International Schools:

Helgaker has been a lecturer at European Summer School in Quantum Chemistry (ESQC) every second year since 1991 and at the summer school Modern Wavefunction Methods (MWM) in Electronic Structure Theory since 2016.



  • Sonia Coriani, Universita’ di Trieste, Italy and the Department of Chemistry, University of Oslo
  • Jürgen Gauss, Johannes Gutenberg Universität Mainz, Germany
  • Mark Hoffmann, University of North Dakota, USA
  • Michal Jaszunski, Polish Academy of Sciences, Warsaw, Poland
  • Hans-Jørgen Aagaard Jensen, University of Southern Denmark, Denmark
  • Poul Jørgensen, Aarhus University, Denmark
  • Henrik Koch, NTNU, Trondheim, Norway
  • Wim Klopper, Karlsruher Institut für Technologie, Germany
  • Claus Jørgen Nielsen, University of Oslo, Norway
  • Jeppe Olsen, Aarhus University, Denmark
  • Elke Pahl, Massey University, Auckland, New Zealand
  • Magdalena Pecul-Kudelska, Uniwersytet Waszawski, Poland
  • Antonio Rizzo, IPFC CNR, Pisa, Italy
  • Kenneth Ruud, University of Tromsø, Norway
  • Trond Saue, Université Paule Sabatier, Toulouse, France
  • Peter Schwerdtfeger, Massey University, Auckland, New Zealand
  • Stella Stopkowicz, Johannes Gutenberg Universität Mainz, Tyskland
  • Dage Sundholm, Helsinki University, Finland
  • Andreas Savin, Sorbonne Université, Paris, France
  • Peter Taylor, Tianjin University, Tianjin, China
  • Andrew Teale, University of Nottingham, UK
  • Julien Toulouse, Sorbonne Université, Paris, France
  • David Tozer, University of Durham, UK
  • Einar Uggerud, University of Oslo, Norway
  • Hans Ågren, KTH, Stockholm, Sweden


  • Magnetic Chemistry (MagiChem),
    FRIPRO, Research Council of Norway, 2019–2022
  • Hylleraas Centre for Quantum Molecular Sciences,
    CoE shared with University Tromsø, Research Council of Norway, 2017–2027
  • Molecules in Extreme Environments,
    Centre for Advanced Study at the Norwegian Academy of Science and Letters, 2017–2018
  • Ab-Initio Adiabatic-Connection Curves for Density-Functional Analysis and Construction (ABACUS),
    ERC Advanced Grant, European Research Council, 2011–2016
  • Molecules in Magnetic Fields (MOLMAG),
    FRIPRO, Research Council of Norway, 2010–2013
  • Centre for Theoretical and Computational Chemistry (CTCC)
    CoE shared with University Tromsø, Research Council of Norway, 2007–2017
  • SCF Methods for Periodic and Non-Periodic Systems,
    FRIPRO, Research Council of Norway, 2006–2009

  • Linear-Scaling Quantum-Chemical Methods for Large Systems,
    FRIPRO, Research Council of Norway, 2003–2005

  • Relativistic Corrections to Molecular Magnetic Properties,
    FRIPRO, Research Council of Norway, 1999–2002


Curriculum vitae can be dowloaded here.

Published Nov. 19, 2010 2:36 PM - Last modified Nov. 15, 2020 6:55 PM