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All isotropy subgroups (and thus all quasicontinuous symmetry changes) corresponding to k points of symmetry have been obtained for the 80 diperiodic space groups. The detailed information for such phase transitions is given here for the diperiodic space group I' —— —. Only two distinct images (sets of representation matrices) occur for this example(More)
We propose a new direct mechanism for the pressure driven ! ! martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.(More)
We have theoretically investigated the mechanism of the pressure-induced reconstructive zinc-blende to rocksalt phase transition in SiC. We obtained 925 possible transition pathways ͑TPs͒ using a group-theoretical analysis method. This extensive survey of possible TPs is a significant feature which distinguishes this study from previous studies. Of these(More)
Martensitic phase transitions appear in a diverse range of natural and engineering material systems. Examination of the energetics and kinetics of the transformation requires an understanding of the atomic mechanism for the transformation. A systematic pathway generation and sorting algorithm is presented and applied to the problem of the titanium ␣ to ␻(More)
Three possible mechanisms for the reconstructive phase transition from the B1 to the B2 structure types are examined: ͑1͒ a modified Buerger ͑MB͒ pathway, ͑2͒ the Watanabe ͑W͒ pathway, and ͑3͒ a new pathway ͑T͒ proposed by Tolédano et al. ͓Phys. Rev. B 67, 144106 ͑2003͔͒. We use first-principles energy calculations to obtain barrier heights for these(More)
A variety of structural transitions in nature do not involve a group-subgroup relationship. A two-dimensional example is the transition between a square lattice and a triangular lattice, which is known to occur in vortex lattices, Wigner crystals, skyrmion lattices, colloids, diblock copolymers, etc. A three-dimensional analog is the shock-induced BCC to(More)