MedeA UNCLE Explore Phase Stability, Bridge the Length Scales

At-a-Glance

MedeA®[1] UNCLE (UNiversal CLuster Expansion) [2],[3] expands access to materials and properties at the mesoscopic and microscopic scales, while retaining the predictive power and accuracy of ab-initio Density Functional Theory (DFT). Explore order-disorder phenomena and phase segregation processes as a function of temperature and composition, and predict additional scalar properties such as band gaps or bulk moduli.

Key Benefits

  • Models systems containing millions of atoms with DFT accuracy

  • Train and evaluate cluster expansions to predict energies and secondary scalar properties such as band gaps or bulk moduli.

  • Streamlined, user-friendly setup within the MedeA Environment

  • Automated, workflow-based refinement of cluster expansions

  • Efficiently manage hundreds of input structures

  • Gain insight with intuitive graphical analysis and visualization tools

  • Flexibly split and restart complex calculations

  • Extend and expand existing cluster expansions with ease

Cluster Expansion with MedeA UNCLE

MedeA UNCLE lets you determine stable multi-component crystal structures and rank metastable structures by enthalpy of formation, while maintaining DFT accuracy. VASP ab-initio calculations are performed on automatically chosen sets of small models to obtain effective interaction parameters. Use these in a Monte Carlo simulation to capture the configurational complexity of real materials at different temperatures.

On the one hand, cluster expansions are used to treat systems ranging from a few up to a million atoms without giving up the accuracy of modern DFT calculations. On the other hand, Monte Carlo simulations permit us to study finite-temperature properties such as short range order phenomena or mixing enthalpies.

Stefan Müller (introduction of [3])

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Ground state diagram (convex hull) for the Cr-Ni system

Tight integration with MedeA‘s job control guarantees ease of use, stability, and fault tolerance. Monitor progress of these fully automated calculations, and use graphical tools to readily visualize results.

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Monte Carlo temperature profile (heating and cooling curves) and simulation cells for a 5 component high-entropy alloy

Properties from MedeA UNCLE

  • Ground state diagram (convex hull)

  • Structures of stable phases

  • Vacancy concentrations

  • Miscibility

  • Random mixing energy

  • Phase stability as a function of temperature and concentration

  • Solubility

  • Order-disorder transition temperature

  • Microstructure

  • Short range order parameter

  • Surface segregation

  • Surface coverage of adsorbents

  • Secondary scalar properties such as mechanical, optical or electronic properties

Computational Characteristics

  • Use Genetic Algorithm or Compressive Sensing

  • Full integration with MedeA VASP and other modules

  • High-throughput using the MedeA JobServer

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NiAl alloy: (100) cut through a 1000 x 1000 x 1000 simulation cell superlattice with 2% constitutional vacancies at T = 500K.

Required Modules

  • MedeA Environment

  • MedeA UNCLE

  • MedeA VASP

Find Out More

Learn more about MedeA UNCLE applications and examples by watching the webinar MedeA UNCLE: Atomistic Studies of Crystalline Systems at Higher Scales.

Find out more by visiting the Materials Design Application Notes:

  • Adaptive Crystal Structures of Au-Cu Alloy

  • Structure and Bonding of Boron Carbide

download:

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