Alan J. H. McGaughey, Professor of Mechanical Engineering at Carnegie Mellon University, has led a collaborative effort to benchmark three widely used open-source packages for lattice thermal conductivity calculations: ALAMODE, phono3py, and ShengBTE. Coordinating what the team called the “Phonon Olympics,” McGaughey brought together developers and expert users to test the consistency and accuracy of these codes, which are essential tools for researchers studying thermal transport in materials.
McGaughey, A. J. H., Lindsay, L., Bao, H., Hamakawa, T., Juneja, R., Li, S., Li, W., Masuki, R., Meng, F., Meng, H., Pandey, T., Shao, C., Shiomi, J., Tadano, T., Togo, A., Wang, A., & Zhang, X. (2025). Phonon Olympics: Phonon property and lattice thermal conductivity benchmarking from open-source packages. Journal of Applied Physics, 138(13). https://doi.org/10.1063/5.0289819
Predicting lattice thermal conductivity is a key part of designing materials for applications such as thermal management in electronics and energy conversion. Many researchers rely on open-source packages that couple density functional theory, phonon lifetimes, and the Peierls-Boltzmann transport equation. Until now, there has been limited benchmarking to determine whether different codes and users produce consistent results, which can make it difficult to interpret predictions or compare findings across studies. McGaughey’s effort aimed to provide clarity and establish best practices for using these computational tools.
Alan J. H. McGaughey, Professor of Mechanical Engineering at Carnegie Mellon University stated,
“Having more researchers in this space will lead to more advancement, but only if their findings are well grounded. A lot of people write code and put it on the internet, but it’s important that they are rigorously checked to make sure they give trustworthy results”.
The study involved six teams, with each of the three packages tested by both the developers and expert users. The teams applied the codes to four materials: germanium, rubidium bromide, monolayer molybdenum diselenide, and aluminum nitride. Each team performed harmonic and cubic force constant calculations, computed phonon lifetimes, and solved the Peierls-Boltzmann transport equation to determine thermal conductivity as a function of temperature. The results showed that thermal conductivities calculated by all teams fell within fifteen percent of the mean value for each material. This consistency suggests that when used properly, the packages provide reliable predictions of thermal conductivity.
The researchers also analyzed sources of variation. Phonon frequencies derived from harmonic force constants were nearly identical across codes, while differences in thermal conductivity mostly arose from how users implemented cubic force constants, including supercell sizes, cutoff distances, atomic displacements, and symmetry handling. By documenting these workflow considerations, the team highlighted the importance of careful user choices in obtaining accurate results.
The study demonstrates that open-source packages can produce reproducible results when used with attention to convergence and workflow details. This is encouraging for materials scientists, engineers, and smaller research teams who may not have access to extensive computational resources but rely on these tools for materials screening and thermal transport studies. At the same time, the authors note that ab initio predictions may still differ from experimental measurements due to inherent approximations, such as neglecting four-phonon scattering or defects, so users should interpret results with care.
The Phonon Olympics also points toward future work. Benchmarking could be extended to more complex materials, including alloys, nanostructures, and systems with defects or interfaces, as well as higher-order scattering effects. Establishing standardized workflows and datasets could further improve reliability, helping the research community advance in a coordinated and reproducible manner.
The benchmarking initiative led by Alan J. H. McGaughey marks a significant step toward increasing confidence in open-source thermal conductivity codes. The findings show that with proper implementation, ALAMODE, phono3py, and ShengBTE provide consistent and reliable results. For engineers and researchers in thermal management, energy materials, and related fields, the study emphasizes the importance of careful workflow management, convergence testing, and documentation to ensure trustworthy computational predictions.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
