diff --git a/docs/5_atoms_and_lcao.md b/docs/5_atoms_and_lcao.md
index 3e4cc99d911df0263f16020181226126885e7f2e..59b5d64bc2f5504b979805af3a20e24590803895 100644
--- a/docs/5_atoms_and_lcao.md
+++ b/docs/5_atoms_and_lcao.md
@@ -357,10 +357,10 @@ where $V_0>0$ is the potential strength, $\hat{p}$ the momentum of the electron,
     The procedure to find the energy and a wave function of a state bound in a $\delta$-function potential, $V=-V_0\delta(x-x_0)$, is similar to that of a quantum well:
 
     1. Assume that we have a bound state with energy $E<0$.
-    2. Compute the wave function $\phi$ in different regions of space: namely $x < x_0$ and $x > x_0$.
-    3. Apply the boundary conditions at $x = x_0$. The wave function $\phi$ must be continuous, but this is not the case for $d\phi/dx$. Instead, due to the presence of the delta-function:
+    2. Compute the wave function $\psi$ in different regions of space: namely $x < x_0$ and $x > x_0$.
+    3. Apply the boundary conditions at $x = x_0$. The wave function $\psi$ must be continuous, but this is not the case for $d\psi/dx$. Instead, due to the presence of the delta-function:
 
-        $$\left.\frac{d\phi}{dx}\right|_{x_0+\epsilon} - \left.\frac{d\phi}{dx}\right|_{x_0-\epsilon}= -\frac{2mV_0}{\hbar^2}\phi(x_0).$$
+        $$\left.\frac{d\psi}{dx}\right|_{x_0+\epsilon} - \left.\frac{d\psi}{dx}\right|_{x_0-\epsilon}= -\frac{2mV_0}{\hbar^2}\psi(x_0).$$
 
     4. Find at which energy the boundary conditions at $x = x_0$ are satisfied. This is the energy of the bound state.
     5. Normalize the wave function.