In the framework of the ab initio random structure search method,we show that elemental Se and Te undergo pressure-induced structural transition from the bcc to fcc phase,in agreement with the theoretical results prev...In the framework of the ab initio random structure search method,we show that elemental Se and Te undergo pressure-induced structural transition from the bcc to fcc phase,in agreement with the theoretical results previously reported.By means of the pseudopotential plane-wave method based on density functional perturbation theory,the fcc structure for both elements is found to be another phonon-mediated superconducting phase of these materials.With a reasonable value for the Coulomb pseudopotentialμ^(*)=0.12,the maximum superconducting transition temperature Tc in the fcc phase of Se and Te is estimated to be about 5.7 K and 4.6 K,respectively.Furthermore,we show that in the entire fcc phase for Se and Te,the superconducting transition temperature decreases together with the increase in pressure,leading to the final suppression of the superconductivity.It is suggested that such behavior is mainly caused by the rapid increase in the mean-square phonon frequency(ω^(2))with pressure.Finally,a very strong electron-phonon coupling value,for both Se and Te in the fcc phase,is found along the G-K high symmetry lines.展开更多
基金Supported by the National Natural Science Foundation of China(Nos 11247222,11164020 and 51001042)Nanyang Nor-mal University Science Foundation(Nos ZX2012018,ZX2010011and nytc2006k102)+3 种基金the Natural Science Foundation of Science and Technology Department of Henan Province(Nos 112102210019 and 112300410121)the Natural Science Foundation of Ed-ucation Department of Henan Province(Nos 2011B140015 and 2010B140012)Higher Education Reform of Henan Province(No 2012SJGLX233),China Postdoctoral Science Foundation(No 20110491317)Young Core Instructor Foundation from the Education Department of Henan Province(No 2012GGJS-152).
文摘In the framework of the ab initio random structure search method,we show that elemental Se and Te undergo pressure-induced structural transition from the bcc to fcc phase,in agreement with the theoretical results previously reported.By means of the pseudopotential plane-wave method based on density functional perturbation theory,the fcc structure for both elements is found to be another phonon-mediated superconducting phase of these materials.With a reasonable value for the Coulomb pseudopotentialμ^(*)=0.12,the maximum superconducting transition temperature Tc in the fcc phase of Se and Te is estimated to be about 5.7 K and 4.6 K,respectively.Furthermore,we show that in the entire fcc phase for Se and Te,the superconducting transition temperature decreases together with the increase in pressure,leading to the final suppression of the superconductivity.It is suggested that such behavior is mainly caused by the rapid increase in the mean-square phonon frequency(ω^(2))with pressure.Finally,a very strong electron-phonon coupling value,for both Se and Te in the fcc phase,is found along the G-K high symmetry lines.
