Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

The single inpurity Anderson Hamiltonian is $H=\sum_{\sigma}\epsilon_{\sigma}n_{d,\sigma}+Un_{d,\uparrow}n_{d,\downarrow}+\sum_{k,\sigma}\epsilon_{k}c_{k,\sigma}^{+}c_{k,\sigma}+\sum_{k,\sigma}(V_{k}c_{d,\sigma}^+c_{k,\sigma}+h.c.)$

where $n_{d,\sigma}$ is the occupation number of d electron and $\epsilon_d$ is the energy level of d electron, $U$ is the Hubbard interaction.

I know that there are several regimes of parameters $\epsilon_d, U, \Delta$ ($\Delta$ is the resonance width. I do not know why it is called resonance width and this is actually my question), in which the physics of anderson model is different.

For example, there are intermediate valence regime where $\epsilon_d$ and $\epsilon_d+U$ are comparable with $\Delta$. For another example, when $\epsilon_d-\epsilon_F>>\Delta$ and $\epsilon_d+U-\epsilon_F<<\Delta$, they are called empty orbit regime.

My questions are

  1. What is the resonance width? What is its physical meaning?

  2. Why should we compare $\epsilon_d-\epsilon_F$ and $\epsilon_d+U-\epsilon_F$ with $\Delta$, rather than 0, when we distinguish different regimes of Anderson Model?

Thanks very much!

share|improve this question

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.