diff --git a/Change_log.md b/Change_log.md
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--- a/Change_log.md
+++ b/Change_log.md
@@ -1,5 +1,6 @@
 # [main](https://github.com/jzhang-github/AGAT/tree/main)
 
+
 # [v9.0.0](https://github.com/jzhang-github/AGAT/tree/v9.0.0)
 **Note: AGAT after this version (included) cannot load the well-trained model before.** If you need to do so, please use v8.0.5: https://pypi.org/project/agat/8.0.5/
 - Fix bugs when traing model with voigt stress tensor.
diff --git a/FAQ.md b/FAQ.md
new file mode 100644
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@@ -0,0 +1,7 @@
+# FAQ
+1. What is the unit of `ase.atoms.get_stress()`?
+
+	`eV/Å^3`.
+
+	Knuth et. al. Comput. Phys. Commun 190, 33-50, 2015
+	https://github.com/atomistic-machine-learning/schnetpack/issues/165#issuecomment-559028863