AI summaryⓘ
The authors developed a new method called thermodynamic interatomic potential (TIP) that helps predict how materials behave at different temperatures and pressures by calculating free energy, not just simple energy. TIP extends existing models to provide more realistic data about phase changes in solids, including tricky cases like phases stabilized by vibrations. Their implemented version, TIP[UMA], can quickly give important material properties like equations of state and phase boundaries from one calculation. This approach also adapts to study alloys, making it easier to explore materials stability under real-world conditions. Overall, the authors aim to make free energy calculations as straightforward as energy calculations for faster materials discovery.
free energyphase stabilityinteratomic potentialGibbs free energyquasi-harmonic approximationmolecular dynamicsequation of statephase transitionalloy solubilitymiscibility gap
Authors
Juno Nam, Bowen Deng, Xiaochen Du, Luis Barroso-Luque, Benjamin Kurt Miller, Rafael Gómez-Bombarelli
Abstract
Free energies govern solid-state phase stability, yet computational materials discovery still relies largely on ground-state energies because free energy calculations require ensemble averages. We introduce the thermodynamic interatomic potential (TIP), which extends an interatomic potential from its static energy to a thermodynamically consistent Gibbs free energy model, with thermodynamic responses following from temperature and pressure by automatic differentiation. We implement TIP[UMA] using the universal potential UMA, train it on free energies from quasi-harmonic to molecular dynamics fidelity, and calibrate it to higher-resolution calculations or experiment. From a single evaluation, it returns the equation of state of a crystal and locates phase transitions among competing branches, including dynamically stabilized phases. Fine-tuning extends the model to alloy solubility limits and miscibility gaps. TIP makes the free energy as accessible as the potential energy, opening finite-temperature phase stability to high-throughput discovery.