Author: Michael Engel

Scientists have long known that the shape of tiny crystals (nanocrystals) can affect their properties, such as how they interact with light or how well they function as catalysts. However, precisely understanding how these shapes form has been challenging, since many factors are involved: temperature, chemicals in the solution, and even the arrangement of atoms at the crystal’s edges. In this study, the researchers introduced a theoretical and computational approach that focuses on the critical spots where atoms attach as the crystal grows. By examining the energy required to add atoms at these sites, they explain why certain shapes, including cubes, octahedra, or other symmetrical forms, often appear.

Beyond explaining why various shapes emerge, this method can guide experimental design. It enables scientists to predict which conditions favor different morphologies and to control crystal growth toward specific outcomes. The study shows that the first atom to grow on the surface, referred to as the adatom, dominates the process by creating temporary pathways that lead to particular shapes. This new understanding not only clarifies how nanocrystals form but also suggests ways to refine their shapes for targeted uses in technology and medicine.

Read about this work here:

Carlos L. Bassani, Michael Engel
Kinetically Trapped Nanocrystals with Symmetry-Preserving Shapes
Journal of the American Chemical Society 147, 9487-9495 (2025)

Surface strain can help increase the performance of nanocatalysts, and we have designed a new strategy to stabilize the surface strain in materials. The groups of Yimo Han and Matthew R. Jones at Rice University synthesized nanoparticles and used four-dimensional scanning transmission electron microscopy (4D-STEM) to capture an electron diffraction pattern at each scan position, which produces detailed structural information. Molecular dynamics simulations of Alberto Leonardi investigated the inhibition of dislocation nucleation due to reduced shear stress at corners.

Read about the research here:

Chuqiao Shi, Zhihua Cheng, Alberto Leonardi, Yao Yang, Michael Engel, Matthew R. Jones, Yimo Han
Preserving Surface Strain in Nanocatalysts via Morphology Control
Science Advances 10, eadp378 (2024)

The lab published two in-depth overview articles in the field of mesostructure formation:

Nanocrystal Assemblies: Current Advances and Open Problems
This review appeared in ACS Nano and is coauthored by 42 authors. The paper grew from discussions on these topics among the participants of the workshop “Nanoparticle Assemblies: A New Form of Matter with Classical Structure and Quantum Function”, held at the Kavli Institute for Theoretical Physics (KITP), Santa Barbara/CA, USA, from March 27 to May 19, 2023. This study is a broader-view study linking different scales, fundamentals, and methods, emphasizing open problems to inspire and push forward research in the field.

Mesomorphology of Clathrate Hydrates from Molecular Ordering
This perspective appeared in the Journal of Chemical Physics. The paper discusses the coupling of molecular ordering with the mesoscales, including (i) the emergence of porous patterns as a combined factor from the walk over the free energy landscape and 3D competitive nucleation and growth and (ii) the role of molecular attachment rates in crystallization–diffusion models that allow predicting the timescale of pore sealing. It discusses the use of discrete models (molecular dynamics) to build continuum models (phase field models, crystallization laws, and transport phenomena) to predict multiscale manifestations at a feasible computational cost.