Univ. of Pennsylvania, Materials Science, 2005 R. H. French http://www.lrsm.upenn.edu/~frenchrh/index.htm April 19, 2023 VuGraph 2

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f Sum Rule / Energy (eV)File # 3 : STOS13BS

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SrTiO3

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Local Optical Properties Of

Grain Boundary

London Dispersion Energies Of Grain BoundariesLondon Dispersion Energies Of Grain Boundaries11

R. H. French (Co-PI) University of Pennsylvania, R. H. French (Co-PI) University of Pennsylvania, DMR-0010062DMR-0010062

1. K. van Benthem, G. L. Tan, L. K. Denoyer, R. H. French, M. Rühle, Physical Review Letters, 93, 227201, (2004). 2. S. Hutt, O. Kienzle, F. Ernst, and M. Rühle, Z. Metallkd. 92, 105 (2001). This work is supported by by NSF Grant No. DMR-0010062 and by the EU under Contract No. G5RD-CT-2001-00586.

The long range London dispersion interactions, a fundamental component of the van der Waals Forces, are universal in physics, chemistry, biology and materials science and arise from the transient induced dipoles of the interatomic bonds exchanging virtual photons.

Our determination of quantitative optical properties of grain boundaries at high spatial resolution has made possible the determination of the Hamaker coefficients of grain boundaries, using our multi-layer, graded interface approach,

We calculate the London dispersion energy is up to 10% of the total grain boundary energy for atomically structured 5 and near-13 grain boundaries of SrTiO3.

This appreciable London dispersion interaction plays a role in determining both the end stage microstructure and properties of grain boundaries in functional materials.

Univ. of Pennsylvania, Materials Science, 2005 R. H. French http://www.lrsm.upenn.edu/~frenchrh/index.htm April 19, 2023 VuGraph 3

Gecko Hamaker: Gecko Hamaker: van der Waals Forces For Educationvan der Waals Forces For Education The London dispersion component of the van

der Waals Forces are long range and universal and play a critical role in physics, chemistry, biology and materials science. Yet they have been neglected in the traditional curricula due to the complexity of their roots in quantum electro dynamics.

Using Gecko Hamaker, students can calculate Full spectral Hamaker coefficients1 of the London dispersion interaction for complex multilayer configurations2 of materials.

This freely available program will allow students to use state of the art methods and materials properties to determine the magnitude of the long range interactions at play in their systems. This program complements the new textbook on van der

Waals forces by V. A. Parsegian3. 1. R. H. French, Journal of the American Ceramic Society, 83, 9, 2117-46 (2000). 2. K. van Benthem,

G. L. Tan, L. K. Denoyer, R. H. French, M. Rühle, Physical Review Letters, 93, 227201, (2004). 3. V. A. Parsegian; van der Waals Forces: A handbook for biologists, chemists, engineers and physicists (Cambridge University Press, 2005 in press). This work is supported by by NSF Grant No. DMR-0010062 and by the EU under Contract No. G5RD-CT-2001-00586.