The Atomic Strain Tensor
Technical rept. 1990-1991,
MASSACHUSETTS INST OF TECH CAMBRIDGE
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A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated into Delauney tetrahedra, identifying interstices, and Voronol polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronol polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronol polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level.