Abstract:

The crystal structure, mechanical, thermodynamic, and electronic properties of the high pressure phase R3m  in BaC₂ were investigaed by means of first\|principle method of the density functional theory. The calculation results show that R3m  phase is a more ionic semiconductor material, compared with the I4mmm phase in BaC₂. The phase transition pressure from I4mmm to R3m  is 3.6 GPa, and agrees with experimental result. The elastic constants of R3m  structure meet the Bonn\|Huang Kun criterion, and thus its lattice is dynamics stable. The population analysis shows that the electron transfer from Ba atom to C atom under high pressure plays an important role in the transition from I4mmm to R3m  phase in BaC₂.

Key words: carbide, electron structure; , high pressure physics