Trygve Helgaker represented the Hylleraas Centre at the international meeting "New Challenges for Ab Initio Theory in Molecular Science", held at the Biological and Chemical Research Centre, Warsaw 1–5 July 2025.
The conference brought together 36 invited speakers and was organized by the University of Warsaw in honour of Bogumił Jeziorski, a prominent Polish quantum chemist who passed away on 15 September 2023.
At the conference Helgaker delivered an invited talk entitled “A Variational Reformulation of Molecular Properties in Electronic-Structure Theory”, presenting a unified variational perspective on molecular response properties.
The conference was organized by Grzegorz Chałasiński (University of Warsaw),Berta Fernández Rodríguez (University of Santiago de Compostela), Michał Lesiuk (University of Warsaw), and Krzysztof Szalewicz (University of Delaware).