|
Joyeon Yi (Pusan Natl. Univ.) This talk presents a quick view on the Green¡¯s function methods. Without presenting lengthy formal preliminaries, we directly jump into some examples for which the Green¡¯s function can be calculated exactly and easily without actually bothering your brain. Yet, the examples show how the Green¡¯s functions account for the system characteristics such as excitation spectrum and conductivity. Next, we go on to a nontrivial example where electron-electron repulsion causes seemingly unmanageable mathematical complexity but plays an essential role in the observed phenomena like Kondo effect. A (hopefully) apprehensible view will be presented along with a brief discussion on theoretical attempts. We also present our method that is impressively simple but well reproduces the results from existing theories (exact diagonalization and numerical renormalization group). We finish with a few words on a system of quantum dot-DNA composite which in fact motivated us to devise the method, and showing some preliminary results. |