中文摘要：

在有效质量近似下,利用久保（Kubo）公式计算了单层石墨片的最小电导率.结果发现最小电导率的大小依赖于准粒子谱函数的函数形式：如果准粒子谱函数取洛伦兹分布,得到最小电导率为4e^2/πh;如果准粒子谱函数满足高斯分布,则最小电导率为2e^2/h.

英文摘要：

Under effective-mass approximation, the Kubo formula is used to calculate the minimal conductivity of graphene. It is found that the minimal conductivity depends on the spectral function of quasiparticle. If the distribution of the spectral function is taken to be Lorentz distribution, the minimal conductivity is 4e2/πh. If the distribution of the spectral function satisfies Gaussian distribution, however, the minimal conductivity is 2e^2/h.