diff --git a/src/8_many_atoms_sol.md b/src/8_many_atoms_sol.md
index 38e736390af468e8f316cc0d673039392b31ff6a..2381766ad8ab71ab5315aee3be94be9ad17476bc 100644
--- a/src/8_many_atoms_sol.md
+++ b/src/8_many_atoms_sol.md
@@ -66,9 +66,10 @@ pyplot.plot(k[199:100:-1],-(t1+t2)*np.cos(k[0:99]/2),'r--',label='1 atom dispers
 pyplot.plot(k[299:200:-1],-(t1+t2)*np.cos(k[300:399]/2),'r--')
 
 pyplot.xlabel('$ka$'); pyplot.ylabel(r'$E-\epsilon$')
-pyplot.xticks([-2*pi, -pi, 0, pi,2*pi], [r'$-2\pi',r'$-\pi$', 0, r'$\pi$',r'$2\pi$'])
-pyplot.yticks([-t1-t2, 0, t1+t2], [r'$-t_1-t_2$', 0, r'$t_1+t_2$']);
+pyplot.xticks([-2*pi, -pi, 0, pi,2*pi], [r'$-2ka$',r'$-ka$', 0, r'$ka$',r'$2ka$'])
+pyplot.yticks([-t1-t2, np.abs(t1-t2), 0, -np.abs(t1-t2), t1+t2], [r'$-t_1-t_2$',r'$-|t_1-t_2|$', '0', r'$|t_1-t_2|$', r'$t_1+t_2$']);
 pyplot.vlines([-pi, pi], -3, 3, linestyles='dashed');
+pyplot.hlines([np.abs(t1-t2),-np.abs(t1-t2)],-2*pi,2*pi, linestyles='dashed');
 
 pyplot.legend(loc='lower center');
 ```