Dirac comb U(x) b→0，V。→0，bV=Y V(x)=y∑(x+na) k'=V2m。-E)/h≈V2m'/h -b0 aa+b 2a+b 2(a+b) By setting y=blo=h2/m, cos ka+ sin ka=cos K(a+b) k --(ma-8是)Dirac comb a b 0 a b  2a b  x U x( ) 2( ) a b           ( ) ( ) 0, , 0 0 V x x na b V bV    k'  2mV0  E/   2mV0 /                           k k a tg k k a K a b k k a bV m 1 2 2 0 1 cos cos sin cos ( ) By setting   /