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lab:research:tmdichal-01 [2014/11/20 21:37] ykkwon [Single-layer MX2] |
lab:research:tmdichal-01 [2014/12/31 15:34] (current) seoung-hun_kang |
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==== Single-layer MX$_2$ ==== | ==== Single-layer MX$_2$ ==== | ||
- | Single-layer MX$_2$ blah blah... | + | We investigate the structural, electronic properties of MX$_2$. |
+ | (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) (X=S, Se) and their phase | ||
+ | transition. We calculate the relative stability of two phase | ||
+ | structures (octahedral-T and trigonal-H) determined by considering | ||
+ | relative positions of X. We find interesting phase existence for | ||
+ | the each group in the periodic table. The stable phase structure | ||
+ | of IV-group (Ti, Zr, Hf) is octahedral, while VI-group (Cr, Mo, W) | ||
+ | is trigonal, and V-group (V, Nb, Ta) is possible two phase structures. | ||
+ | Two phase structures of MX$_2$ have a same total energy at the same | ||
+ | lattice constant near the each most stable lattice constant. | ||
+ | From these results, we also study activation energy barriers | ||
+ | at the various lattice constants such as from stable T phase to H phase, | ||
+ | same total energy, and from stable H to T. Interestingly | ||
+ | we find that the activation energy barrier is small at the small and | ||
+ | large lattice constants for the stable lattice constants. | ||
+ | It means that the phase transition occurs by compressive and tensile strains. | ||