预备知识:傅立叶变换( Fourier transformation) →F(k)=f(r)e"ar→ f(r)= F(ke dkF(k) = f (r) -¥ +¥ ò e ik•r dr f (r) = F(k) -¥ +¥ ò e -ik•r dk 预备知识：傅立叶变换（Fourier transformation)