update authors

AUTHORS.md

@@ -4,8 +4,10 @@ The following people contributed to making of these lecture notes:
 * Bas Nijholt
 * Iacopo Bertelli
 * Joana Fraxanet Morales
+* Kevin Choi
 * Piotr Benedysiuk
 * Sander Otte
+* Sathish Kumar RK
 * Toeno van der Sar
 
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src/8_many_atoms.md

@@ -17,7 +17,7 @@ pi = np.pi
 
     After this lecture you will be able to:
 
-    - formulate equations of motion for electrons or phonons in 1D, for systems with multiple degrees of freedom per unit cell.
+    - formulate equations of motion for electrons or phonons in 1D, with multiple degrees of freedom per unit cell.
     - solve these equations to arrive at the dispersion relation.
     - derive the group velocity, effective mass, and density of states.
     - explain what happens with the band structure when the periodicity of the lattice is increased or reduced.