Ab Initio Construction of Structure-Property Relationships

Axel van de Walle, California Institute of Technology, DMR 0907669

• Structure-property relationships: Guide for materials discovery.

• Project focus: Effect of the symmetry of a crystal on its properties, e.g.:

• elastic and dielectic constants• surface energies, etc.

and how they change with direction (anisotropy).

• Novel aspect:Methodology based on first-principles electronic structure calculations.

• First year’s main findings:Found general mathematical “bases” to represent anisotropic properties for all of the 32 possible crystallographic point symmetry groups.

All crystallographic point symmetry groups (m: mirror, #: #-fold rotation, -: inversion ). Insets show examples of symmetry-adapted bases for anisotropic properties (first few terms shown).

1 1 2 m

2/m 3 3 3m

3m 32 4 4

422 4mm 4/m 4/mmm

42m 6 6 622

6mm 6/m 6/mmm 6m2

222 mmm mm2 m3m

m3 432 43m 23

The methods devised under this grant have been implemented within the PI's widely used Alloy Theoretic Automated Toolkit (ATAT), a software package enabling atomistic and thermodynamic modeling of alloys. This package is freely available on the world-wide web:

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Broader Impacts

Axel van de Walle, California Institute of Technology, DMR 0907669

http://www.its.caltech.edu/~avdw/atat

Research groups using ATAT worldwide.