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Trygve Ulf Helgaker

Professor - Theoretical chemistry
Image of Trygve Ulf Helgaker
Norwegian version of this page
Phone +47-22855428
Room V236
Visiting address Sem Sælands vei 26 Kjemibygningen 0371 OSLO
Postal address Postboks 1033 Blindern 0315 OSLO
Other affiliations Department of Chemistry


Trygve Helgaker works in the area of molecular electronic-structure theory—in particular, wit the development and application of methods for quantum-mechanical simulations of molecular systems. With the emergence of powerful computers and the development of sophisticat simulation models and techniques, quantum-chemical simulations have become an indispensable too to 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, it 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 or thousands of atoms such as those encountered in biological systems. 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.

Since the 1980s, Trygve Helgaker has developed the quantum-chemistry program system Dalton in cooperation with other researchers in Scandinavia. Dalton has been licensed to almost 2000 research groups worldwide and is one the most flexible program systems in quantum chemistry.

For popular accounts of quantum chemistry, see an article in Apollon and a lecture on quantum chemistry.


Trygve Helgaker (f. 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 Faculté de Chimie, 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. Helgaker is the director of the  Centre for Theoretical and Computational Chemistry (CTCC), a Centre of Excellence shared with the University of Tromsø 2007–2017.

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?


Helgaker has published 288 ISI-registered articles, which have been cited more than 17000 times. He is Norway's most cited chemist and has an H-index of 65. His publication list and all publications can be downloaded here.

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 1700 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 83 lectures at international meetings and conferences, 49 guest lectures at departments and research institutions, and 236 lectures at international summer and winter schools in quantum chemistry. Many of his 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.

European Summer School in Quantum Chemistry (ESQC)

Since 1991, Helgaker has been a lecturer at the European Summer School in Quantum Chemistry (ESQC),  held biennially near Palermo in Sicily. For his talks given at ESQC, see here.



  • Sonia Coriani, Universita’ di Trieste, Italy and the Department of Chemistry, University of Oslo
  • Jürgen Gauss, Johannes Gutenberg Universität Mainz, Germany
  • Nicholas Handy, University of Cambridge, UK
  • 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
  • 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
  • Andreas Savin, Université Pierre et Marie Curie, Paris, France
  • Peter Taylor, University of Melbourne, Australia
  • Andy Teale, University of Nottingham, UK
  • Julien Toulouse, Université Pierre et Marie Curie, Paris, France
  • David Tozer, University of Durham, UK
  • Einar Uggerud, University of Oslo, Norway
  • Hans Ågren, KTH, Stockholm, Sweden


  • Centre for Theoretical and Computational Chemistry (CTCC),
    a CoE shared with the University of Tromsø, RCN, 2007–2017
  • Molecules in magnetic fields (MAGMOL), FRIPRO, RCN, 2010–2013
  • Ab-initio adiabatic-connection curves for density-functional analysis and construction (ABACUS), ERC Advanced Grant, ERC, 2011–2016


Curriculum vitae can be dowloaded here.



All publications can be downloaded here.

Published Nov 19, 2010 02:36 PM - Last modified Apr 17, 2015 10:12 AM