1. Ideal Mechanical Strength Lindsay O’Brien, Course 22 9/27/12

2. Clarification of Variables VariableUnitsDescription eV/atomBinding energy per atom --Shear elastic strain --Hydrostatic invariant GPaShear modulus GPaBulk modulus m2m2 Slip plane area --Bravais translational vector energy/areaGeneralized stacking fault energy/areaUnstable stacking energy

3. Potential Learning Landscape Metallic Bonding Explanation of Metal Properties Metastable State of Matter Binding Energy Ideal Strength Potential Energy Landscape Thought Experiment Versus Frenkel Sinusoidal Shear Modulus G, Bulk Modulus B Dislocations Types of Dislocations Explanation of Strength Discrepancies

4. Potential Energy Landscape Activation Energy Turning Point Things to Remember: First derivative of potential is force Force = 0 corresponds to minimum or saddle point When the second derivative of potential is zero, you’re at a turning point Convex Concave http://www.engr.ucsb.edu/~shell/che210d/Exploring_the_energy_landscape.pdf

5. Shear and Bulk Moduli Hydrostatic!

6. Measurement of Ideal Stress Assumptions Perfect lattice with no defects Temperature = 0 K ɛ hydro ɛ shear Oh no!

7. Prove it! Electron glue is local (only care about atomic planes directly below and above)

8. Further Simplification Small Deformation (Small x) Large Deformation (Large x)

9. Thanks!