Seminarium CeNT (piątek, 24 kwietnia 2026): Bridging Experiment and Theory: Dynamic Quantum Crystallography for Exploring Polymorphism

20 04 2026

Centrum Nowych Technologii Uniwersytetu Warszawskiego zaprasza na seminarium:

dr hab. Anna Hoser

Wydział Chemii, Uniwersytet Warszawski

Tytuł: Bridging Experiment and Theory: Dynamic Quantum Crystallography for Exploring Polymorphism
Data: Friday, April 24, 2026
Czas: 12:00 (Central European Time)
Prowadzący: prof. Bartosz Trzaskowski

Seminarium odbędzie się w audytorium 00.142 w CeNT (Banacha 2C)

Abstrakt:

Polymorphism—the ability of a compound to exist in at least two different arrangements of the molecules of that compound in the solid state—remains one of the key challenges in understanding the structure–property relationships of molecular materials.1 Different polymorphic forms may differ significantly in solubility, stability, mechanical behaviour, or thermodynamic properties, making the identification of the most stable form and the prediction of potential undiscovered structures an essential yet difficult task. These difficulties arise not only from the subtle energetic differences between polymorphs, but also from the need to accurately account for lattice dynamics and entropy, which remain challenging for purely theoretical approaches.

In this talk, I will present the Normal Mode Refinement (NoMoRe) method2-4, developed by us, in which selected vibrational mode frequencies obtained from periodic DFT calculations are refined directly against high-quality single-crystal X-ray diffraction data. This approach allows us to obtain highly accurate anisotropic displacement parameters (ADPs), including for hydrogen atoms, and enables the reliable extraction of thermodynamic properties such as heat capacities and entropies for molecular crystals—quantities that remain difficult to compute with sufficient precision using theoretical methods alone. By refining vibrational contributions against experimental data, NoMoRe effectively bridges computational models and real crystal behaviour, offering a unique route to quantifying subtle energetic differences between polymorphs.

By merging theory and experiment, we aim to achieve a deeper, quantitatively accurate understanding of the stability and energetic landscape of molecular crystals. I will present case studies—including the pharmaceutical polymorphs pyrazinamide5 and piracetam, the jumping crystal L-pyroglutamic acid6, and related systems—illustrating how dynamic quantum crystallography provides new insights into polymorphism, supports crystal-structure prediction efforts, and helps bridge the long-standing gap between computational models and experimentally observed crystalline forms. Finally, I will pinpoint new directions of our developments (initial models from machine learning potential for NoMoRe) and I will discuss several molecular crystals that continue to challenge current computational methods, highlighting where further methodological development is needed.

[1] J. Bernstein “Polymorphism in molecular crystals”, Second Edition, Oxford University Press, 2020 [2] A. A. Hoser and A. Ø. Madsen, Acta Cryst. A, 2016, 72, 206-214.
[3] A. A. Hoser, M. Sztylko, D. Trzybiński and A. Ø. Madsen, ChemCommun., 2021, 57, 9370- 9373. [4] H. Butkiewicz, M. Chodkiewicz, A. Ø. Madsen, A. A. Hoser, 2025 IUCrJ, 12, 123-136
[5] A. A. Hoser, T. Rekis, A. Ø. Madsen, Acta Crystallographica Section B, 2022, 78, 416-424 [6] A. A. Hoser, T. Rekis, H. Butkiewicz, K. Be̅rziņš, A. S. Larsen, A. Bosak, B. J. Boyd, A. Madsen, 2025, Cryst.Growth Des. 25, 3, 593–602