Large-scale molecular dynamics of cascade production of the primary damage state are performed in fcc nanocrystalline Ni of average grain diameters of 5 and 12 nm. Primary knock-on atom kinetic energies of 5-30 keV are simulated. During the thermal spike phase, significant atomic motion towards the surrounding grain boundary structure is observed, characterized by many replacement-collision sequences. Upon resolidification, the excess volume condenses to form vacancy dominated defects with a complex partial dislocation network forming at higher energies.

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Simulations of nanocrystalline materials reveal that the pressure gradient present within the structure can play a key role in the movement of self-interstitial atoms ͑SIA's͒ to surrounding grain boundaries and therefore in the resulting defect structure formed during displacement cascades. Initially SIA's sense the grain boundary region as a ''defect collector plate,'' a two-dimensional ͑2D͒ indistinguishable region under tension to which they are attracted. The SIA's approach the ''defect collector plate'' and at a certain distance are able to distinguish the local variations in pressure specific to the particular grain boundary misorientation, changing their direction in response to the local pressure environment. Consequently even large SIA clusters undergo a change in direction, moving 1D/3D in order to reach and follow a lower compressive and where possible a tensile pressure path to the grain boundary.

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A 'forward walking' Green's Function Monte Carlo algorithm is used to obtain expectation values for SU(3) lattice Yang-Mills theory in (3+1) dimensions. The ground state energy and Wilson loops are calculated, and the finitesize scaling behaviour is explored. Crude estimates of the string tension are derived, which agree with previous results at intermediate couplings; but more accurate results for larger loops will be required to establish scaling behaviour at weak coupling.

Synergistic synchrotron x-ray absorption experiments using imaging magnetic microspectroscopy, x-ray magnetic circular dichroism, and ab initio calculations on FeCr alloys reveal that the Cr content strongly influences the ferromagnetic microstructure and the Fe magnetic moments. The Cr local structure resolved by extended x-ray absorption fine structure (EXAFS) is also found to be affected by the alloy's composition. Both EXAFS and ab initio calculations show a change in the Cr local atomic structure above 10 at.% Cr content from the distance contraction of the first two coordination shells around the Cr absorbing atom. These results indicate the strong dependence of magnetic and structural properties of these alloys on Cr concentration.

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