From 3170fc4b5c915669cf209a521e551115a9bd0809 Mon Sep 17 00:00:00 2001
From: Prefetch
Date: Wed, 20 Oct 2021 11:50:20 +0200
Subject: Expand knowledge base

---
 content/know/concept/lindhard-function/index.pdc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'content/know/concept/lindhard-function')

diff --git a/content/know/concept/lindhard-function/index.pdc b/content/know/concept/lindhard-function/index.pdc
index d38dc2e..96244c9 100644
--- a/content/know/concept/lindhard-function/index.pdc
+++ b/content/know/concept/lindhard-function/index.pdc
@@ -13,6 +13,11 @@ markup: pandoc
 
 # Lindhard function
 
+The **Lindhard function** describes the response of an electron gas
+to an external perturbation,
+and can be regarded as a quantum-mechanical
+alternative to the [Drude model](/know/concept/drude-model/).
+
 We start from the [Kubo formula](/know/concept/kubo-formula/)
 for the electron density operator $\hat{n}$,
 which describes the change in $\expval{\hat{n}}$
@@ -396,7 +401,7 @@ $$\begin{aligned}
 \end{aligned}$$
 
 Therefore, by inserting all the above expressions,
-we arrive at the following dielectric function $\varepsilon_r$
+we arrive at the Lindhard dielectric function $\varepsilon_r$
 for a non-interacting electron gas in a uniform potential:
 
 $$\begin{aligned}
-- 
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