an impurity interacting with two atoms

$$H = \sum_{\langle ij \rangle } t c_i c_j + f d^+_0 d_0 + ( s c^+_0 d_0 + s c^+_1 d_0 +{\rm h.c.} )$$ (255)

The conductance of this model is calculated as

$$T= \frac{16 \Gamma _0^2 (s^2-ft+tw)^2} { \left( \Gamma _0^... ... -2 ft + f\omega -\Gamma _0\omega +2t \omega -w^2)^2 \right) }$$ (256)

A position of a dip structure is not necessarily at $\omega =f$. The dip appears at $\omega =f-s^2/t$ in this case.