when |y| is large, the logarithmic terms cancel out. Then, Equation (101) can be 

 expressed in a manner similar to Equation (30) 



2D 



, r k(z+C) w N if k(z+^) w , ^ 



= 1 J /;^ ^(y-^) dk + i cos k(y4-n) ^^ 



IT J K-k 7T J K-k ' 



Equation (102) can be further transformed with the exponential integrals as shown in 

 Equation (31). As |y| becomes large, these exponential integrals become small. 

 Finally, as |y| becomes large. Equation (102) can be expressed as 



G^^ = -i e^(-+^) [e^^ly-^l +e^^ly+^l] (103) 



Then, the potential function is given by 



+ J aL-ie'^^^^^) e^^ly-^^l] d£ 

 c 



„ . Kz iKy 

 = -2i e e 



a e''^^ cos Kn d£ (104) 



Equating Equation (99) with Equation (104) , we have the following relation between 

 o and a 



/ 



a = 2 I a e^^ cos Kn d£ (105) 



27 



