超高压下碳结构的第一性原理研究

First principle studies of carbon structure under super-high pressure

采用第一性原理密度泛函理论,结合平面波赝势和广义梯度近似(GGA)方法计算了多种碳结构在超高压条件下的热力学稳定性及晶体结构性质.计算结果表明,碳结构的质量密度和基态能量与其对称性高低没有很强的依赖关系;在超高压条件下,随着压强的增加,热力学相对稳定的碳结构依次是石墨、金刚石、BC-8和SC碳结构,Clark等人所提出的R8结构并不是一种真正的高压稳定碳结构.

Thermodynamic relative stability and crystal structure properties for different carbon structures are studied by using density functional theory and plane - wave pseudopotential technique with generalized gradient approximation, and the following results are obtained. There is no strong dependence relation between the crystal structure symmetry and ground energy or mass density of carbon structure. With increase of pressure, the relative stability sequences for carbon structure are graphite, diamond, BC- 8 and SC structure in turn. The R8 structure of Clark et al is not a true stability phase under high pressure.