A team of researchers advance predictive materials science for high-pressure, high-temperature environments using first-principles HPC workflows.
Application sectors: Aerospace, Energy & extreme-environment engineering, Advanced alloys & metallurgy.
Keywords: thermoelasticity, DFT, high-pressure materials, elastic constants, HPC.
Understanding how materials respond elastically under combined high pressure and temperature is essential for designing components in extreme environments. Osmium, a dense hexagonal close-packed (hcp) transition metal, is particularly interesting due to its exceptional stiffness, high melting point, and use in strengthening platinum-group alloys. However, its thermoelastic properties, especially their temperature dependence, have remained only partially characterized, with limited experimental data and scarce theoretical predictions beyond 0K.
This study delivers the first comprehensive temperature- and pressure-dependent elastic constants (ECs) of osmium using first-principles methods within the quasi-harmonic approximation (QHA). A key result is that QHA predictions closely match experimental measurements in the 5–301 K range, outperforming the widely used quasi-static approximation (QSA). The work also validates important computational simplifications:
- The zero static internal stress approximation (ZSISA) introduces negligible errors compared to full free energy minimization.
- The volume-constrained ZSISA (V-ZSISA) has only minor effects, even in a system like osmium where structural anisotropy behaves differently from lighter metals like beryllium.
Additionally, the study provides new predictions up to 1600 K and 150 kbar, revealing near-linear pressure dependence of ECs and distinct thermal trends: some elastic constants soften with temperature, while others increase. These insights fill a critical gap for high-performance material design.
The research was based on density functional theory (DFT) calculations carried out using MaX lighthouse code Quantum ESPRESSO. This suite enables highly accurate electronic structure, phonon, and thermodynamic calculations required for QHA modeling.
Implications
This study establishes a robust, validated framework for predicting thermoelastic properties of complex metals under extreme conditions. The key takeaway is that QHA combined with efficient approximations delivers near-experimental accuracy while remaining computationally feasible on modern HPC systems. The demonstration that simplified approximations (ZSISA, V-ZSISA) remain accurate even in anisotropic systems like osmium significantly lowers the barrier to large-scale simulations. This opens the door to high-throughput thermoelastic screening of advanced materials.
Interested in applying HPC-driven thermoelastic modeling to your materials? Explore the Quantum ESPRESSO ecosystem or connect with the MaX Centre of Excellence to access workflows, expertise, and code repositories.
Reference paper
High-pressure and high-temperature thermoelasticity of hcp osmium from ab initio quasiharmonic theory
X. Gong and A. Dal Corso, Physical Review B, 112 (2), 024103 (2025), https://doi.org/10.1103/j1sn-dqbl.