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 meso and micro scale, while maintaining the predictive power and accuracy of ab-initio Density Functional Theory (DFT) methods. Explore order-disorder phenomena and phase segregation processes as a function of temperature and composition.

Key Benefits

  • Models systems containing millions of atoms with DFT accuracy
  • User friendly setup within MedeA Environment
  • Workflow based automation of cluster expansion refinement
  • Efficient handling of hundreds of input structures
  • Intuitive graphical analysis and visualization
  • Split and restart complex calculations
  • Extend and expand existing Cluster Expansions

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

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 JobServer and TaskServer
  • 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
[1]MedeA and Materials Design are registered trademarks of Materials Design, Inc.
[2]D Lerch, O Wieckhorst, G L W Hart, R W Forcade, and S Müller, Modelling and Simulation in Materials Science and Engineering 17, no. 5 (June 4, 2009): 055003.
[3]Stefan Müller, “Bulk and Surface Ordering Phenomena in Binary Metal Alloys”, Journal of Physics: Condensed Matter 15, no. 34 (August 15, 2003): R1429–R1500.
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