There are two types of form of coordinate stretched factor. The first is: $$s_w=\kappa_w + \frac{\sigma_w}{j\omega\epsilon_0},$$ and the other is: $$s_w=\kappa_w + \frac{\sigma_w}{a_w + j\omega\epsilon_0}.$$ Here, we adopt the second one.
$k_{max}=5 ~--~ 11$, There is 8. $d$ is the width of the PML layer. $m$ is a integer, we set $m=4$.
if $\sigma=\sigma_m=0$, so,$CA(m)=1, CB(m)=\frac{\Delta t}{\epsilon}, CP(m)=1, CQ(m)=\frac{\Delta t}{\mu}$