中文摘要：

利用晶体结构预测软件USPEX找到了一种Bi的高压稳定相C4,其空间群是： .采用投影缀加平面波方法和广义梯度近似的第一性原理计算,研究了该新结构和Bi 的A7 结构、高压下的单斜结构（Bi-Ⅱ相）、Host-guest 结构（Bi-Ⅲ相）和bcc结构（Bi-Ⅴ相）在不同压强下的压缩行为.拟合出了状态方程,得到各相之间的能量压力关系,进而分析了各相发生相变时的压强.对比发现：常压下C4 结构与bcc 结构的能量非常接近,前者仅仅比后者低10 3 eV/atom.随着压强的升高,发现在50 GPa时C4 结构比bcc结构的能量低10 2eV/atom.运用基于密度泛函微扰理论的赝势平面波方法的ESPRESSO 软件包,计算了C4 结构与bcc 结构在10 GPa压强下的电声耦合常数,从而推算出两者相应的超导转变温度分别是5.8K和7.4K.另外发现两者随着压强的升高而均呈现降低的趋势,在50 GPa时, C4 结构与bcc 结构的分别是1.5 K和1.8 K.

英文摘要：

By using the algorithm implanted in USPEX code, a stable orthorhombic C4 structure (S. G.:) of Bismuth is found in high pressure. The compression behaviors of the C4 structure as well as the A7 structure, the monoclinic Bi-Ⅱ, the complex incommensurate host-guest Bi-Ⅲand the bcc Bi-Ⅴunder different pressure are calculated. The equation of states and the phase transitions among the structures are obtained. It is found that the structure at ambient pressure resembles the bcc structure with the former having enthalpy only 10 3 eV/atom lower than that of the latter. As pressure is increased to 50GPa, the enthalpy difference becomes to 10 2 eV/atom. The electron-phonon coupling (EPC) parameter of the C4 and bcc structure under different pressure are calculated, revealing the critical temperatures of superconductivity ( ) of the C4 and bcc structures is 5.8 K and 7.4 K, at ambient pressure and, when the pressure increases to 50 GPa, the temperature becomes 1.5 K and 1.8 K.