From b8dc0f6343b474e61ee478708cccd0ac2d3ffc2e Mon Sep 17 00:00:00 2001
From: "T. van der Sar" <t.vandersar@tudelft.nl>
Date: Mon, 14 Jan 2019 20:38:17 +0000
Subject: [PATCH] Update lecture_6.md - first formulation of learning goals

---
 src/lecture_6.md | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/lecture_6.md b/src/lecture_6.md
index fa031cb3..338942d8 100644
--- a/src/lecture_6.md
+++ b/src/lecture_6.md
@@ -10,20 +10,25 @@ pi = np.pi
 _(based on chapters 15–16 of the book)_  
 Exercises 15.1, 15.3, 15.4, 16.1, 16.2
 
+!!! summary "Learning goals"
+
+    After this lecture you will be able to:
+
+    - formulate a general way of computing the electron band structure - the **Bloch theorem**.
+    - discuss that in a periodic potential all electron states are Bloch waves.
+    - derive the electron band structure when the interaction with the lattice is weak using the **Nearly free electron model**.
+
+    
+
 Let's summarize what we learned about electrons so far:
 
 * Free electrons form a Fermi sea ([lecture 2](lecture_1.md))
 * Isolated atoms have discrete orbitals ([lecture 3](lecture_3.md))
 * When orbitals hybridize we get *LCAO* or *tight-binding* band structures ([lecture 4](lecture_4.md))
 
-In this lecture we:
+The nearly free electron model (the topic of this lecture) helps to understand the relation between tight-binding and free electron models. It describes the properties of metals.
 
-* Formulate a general way of computing the electron band structure, the **Bloch theorem**.
-* Derive the electron band structure when the interaction with the lattice is weak using the **Nearly free electron model**. This model:
-    - Helps to understand the relation between tight-binding and free electron models
-    - Describes the properties of metals.
-
-All the different limits can be put onto a single scale as a function of the strength of the lattice potential $V(x)$:
+These different models can be organized as a function of the strength of the lattice potential $V(x)$:
 
 ![](figures/models.svg)
 
@@ -142,6 +147,13 @@ Extended BZ (n-th band within n-th BZ):
 * Easy to relate to free electron model
 * Contains discontinuities
 
+!!! summary "Learning goals"
+
+    After this lecture you will be able to:
+
+    - describe how an insulating or conducting nature of a material is related to the material's band structure.
+    - examine 1D and 2D band structures and argue if you expect the corresponding material to be an insulator/semiconductor or a conductor.
+    
 ## Band structure
 
 How are material properties related to the band structure?
-- 
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