Add "Dirac notation" + tweak "Bloch's theorem"

1 files changed, 1 insertions, 1 deletions

diff --git a/latex/know/concept/blochs-theorem/source.md b/latex/know/concept/blochs-theorem/source.md
index 2307d2e..528c218 100644
--- a/latex/know/concept/blochs-theorem/source.md
+++ b/latex/know/concept/blochs-theorem/source.md
@@ -27,7 +27,7 @@ known as *Bloch functions* or *Bloch states*.
 This is suprisingly easy to prove:
 if the Hamiltonian $\hat{H}$ is lattice-periodic,
 then it will commute with the unitary translation operator $\hat{T}(\vec{a})$,
-i.e. $\comm{\hat{H}}{\hat{T}(\vec{a})} = 0$.
+i.e. $[\hat{H}, \hat{T}(\vec{a})] = 0$.
 Therefore $\hat{H}$ and $\hat{T}(\vec{a})$ must share eigenstates $\psi(\vec{r})$:
 
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