2025 marks 100 years since the development of Quantum Mechanics, a breakthrough that reshaped our understanding of the world. To celebrate this milestone, IUCr Journals presents a focused issue on Quantum Crystallography, bringing together cutting-edge research from across our journals.

The full obituary for Sine Ydun Larsen (1943–2025) is published in Acta Cryst. A81.

Lecture 44: Louis Massa (Hunter College, The City University of New York, USA): "Energy formalism of an X-ray electron density of large biological molecules"

The next two online lectures in the monthly series of Distinguished Lectures on Quantum Crystallography and Complementary Fields will be presented on Thursday 6 March 2025 at 16:00 CET. Register here to attend.