Computer simulation and particular properties of Sigma=3(n) boundaries and their groups

Algorithms and programs have been developed to analyze and predict experimental data on processes of multiple twinning and particular properties of Sigma = 3(n) grain boundaries, such as faceting, formation of multiple junctions and nodes etc. The system involves programs to determine I)crystallographic parameters of Sigma = 3(n) boundaries on the basis of quaternion method; 2) the class of equivalent rotations for an arbitrary value of the reverse density of coincidence sites (Sigma); 3) elementary vectors and the space symmetry of coincidence lattices and interfaces; 4) plotting of atomic models of multiple junctions of Sigma = 3(n) grain boundaries etc. to simulate real processes in f.c.c. materials with low value of stacking fault energy. Topological structural ''chain'': boundary-junction-node-grain, based on symmetry arguments and computer simulation is analyzed. The symmetry properties of multiple junctions and nodes with Sigma = 3(n) boundaries are established.