meep中，定义金属的德鲁得洛伦兹模型，用于定义金属的介电常数的源代码-meep, define metal Drew Lorentz model was used to define the dielectric constant of the metal

计算金属的介电常数,，准确的说是Drude-Lorenz模型(It can be used to calculating the permittivity of metal)