I just found a few interesting articles related to density matrices and Green’s functions:

- Challenges in Truncating the Hierarchy of Time-Dependent Reduced Density Matrices Equations: Open Problems by Akbari
*et al.*(ArXiv) - Levels of self-consistency in the GW approximation by Stan, Dahlen, and van Leeuwen.
- Wick Theorem for General Initial States by van Leeuwen and Stefanucci (this is an interesting generalization to the time-dependent case of the Mukherjee and Mukherjee-Kutzelnigg generalized normal ordering).

There are interesting parallels between these works and papers published in the quantum chemistry literature. And why not, let’s add a little debate on TD-DFT:

- Is time-dependent density functional theory formally exact? (from ArXiv but also check the published version, it could be different) by Schirmer and Dreuw.
- Comment on “Critique of the foundations of time-dependent density functional theory” [Phys. Rev.A. 75, 022513 (2007)] by Maitra, Burke, and van Leeuwen.