y-> ■ 



2B 



-q(x+B) 



-q(x-B) 



e~ qx 



v qs 



(F7) 



where 



(F8) 



3. Equations F6 and F7 are easily transformed term by term (see 

 Appendix A) to yield Equations 103 and 104 (main text). 



F2 



