Plans for week 43, October 24-28

Dear all, the aim this week is to get started with many-body perturbation theory, starting with a time-independent derivation and thereafter moving to a diagrammatic representation and time-dependent perturbation theory.  We start on Thursday by linking FCI theory and Hartree-Fock with many-body perturbation theory by reminder ourselves about Thouless' theorem.  The exercise this week is (perhaps) a final word on the Lipkin model with applications of Hartree-Fock theory to the model plus a discussion of the stability of the Hartree-Fock method in terms of the interaction strength parameters.

The plan for the week is as follows:

* Topics to be covered

  o Thursday:

    * Linking FCI and Hartree-Fock theory with many-body perturbation theory

    * Time-independent perturbation theory

  o Friday:

    * Time-dependent perturbation theory and diagrammatic representation

* Lecture Material: slides for week 43, handwritten notes and Shavitt and Bartlett chapter 4 and sections 5.1-5.3

* Seventh exercise set at https://github.com/ManyBodyPhysics/FYS4480/blob/master/doc/Exercises/2022/ExercisesWeek43.pdf