Science and Software for Predictive Simulation of Chemo-mechanical Properties in Real Materials

R. J. Bartlett, H-P. Cheng, & S.B. Trickey, U. Florida, DMR-0325553

Forming and breaking chemical bonds under mechanical stress is vital in many industrial processes. Predictive simu-lations of such chemo-mechanical processes fundamentally require quantum mechanical descriptions. State-of-the-art QM calculations are limited in the number of atoms that can be handled. To beat this limitation, requires fast approximate QM and a multi-scale approach to embed the QM region in a much larger classical one. Nanorod fracture treated with a new pure fast QM scheme we developed is very different from all-classical fracture – and much more realistic!

An all-QM silica nanorod fractures under uniaxial strain (movie)

Science and Software for Predictive Simulation of Chemo-mechanical Properties in Real Materials

R. J. Bartlett, H-P. Cheng, & S.B. Trickey, U. Florida, DMR-0325553

Here is a movie of water dissociation on the amorphous silica surface from the hybrid quantum-classical model; only the QM region is shown

Water weakens silica dramatically.Why? How? Quantum-mechanicsis essential for realism, classical mechanics for speed. Here’s ahybrid silica surface model. The QM region contains 31,74, &209 Si,O atoms in the threeboxes, repectively

Science and Software for Predictive Simulation of Chemo-mechanical Properties in Real Materials

R. J. Bartlett, H-P. Cheng, & S.B. Trickey, U. Florida, DMR-0325553

How does water interact with the nanorod? Understanding this would give us a leg up on how to embed the QM regime in a proper classical regime. In this movie, we look down on silica rings from the middle of the nanorod and watch a water dimer help break a silicon-oxygen bond. Notice the similarity with the amorphous surface in the hybrid simulation.

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