diff --git a/README.md b/README.md
index 5f36ee4..b62d841 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
-# OpenChemistry Molecules
+# Molecules
+===========
 
-Common molecule fragments for visualization in Avogadro.
-Includes a variety of organic functional groups, including:
+Common molecule fragments including a variety of organic functional groups:
 
 - alcohols
 - aldehydes
@@ -31,3 +31,8 @@ Includes a variety of organic functional groups, including:
 - steroids
 - sulfoxides
 - thiols
+
+All molecules are made available the BSD license. Most are from the
+[Blue Obelisk Chemical Structures](http://chem-file.sourceforge.net/) set.
+Where possible, optimized geometries are made available using the
+[Pitt Quantum Repository](https://pqr.pitt.edu/)
diff --git a/plugin.json b/plugin.json
new file mode 100644
index 0000000..e243b8a
--- /dev/null
+++ b/plugin.json
@@ -0,0 +1,7 @@
+{
+  "author": "Geoffrey Hutchison",
+  "version": 1.0,
+  "name": "crystals",
+  "url": "https://github.com/openchemistry/crystals",
+  "description": "Set of over 500 common crystal structures.",
+}