confinement energies vs potential height for a 2D hexagonal well with
barrier height V_0, diameter L (vertex-to-vertex), and effective mass m*
U_0 = hbar^2 / 2 m* L^2
For m* = m_e and L = 1 nm, U_0 = 38.10 meV

V_0/U_0   	E_1/U_0   	E_2/U_0   	E_3/U_0   	E_4/U_0
2.000e+03	2.786e+01	7.056e+01	1.262e+02	1.458e+02	
1.000e+03	2.769e+01	7.014e+01	1.255e+02	1.449e+02	
5.000e+02	2.743e+01	6.947e+01	1.243e+02	1.435e+02	
2.500e+02	2.702e+01	6.845e+01	1.225e+02	1.414e+02	
1.250e+02	2.644e+01	6.698e+01	1.198e+02	1.384e+02	
6.250e+01	2.563e+01	6.491e+01	1.161e+02	1.340e+02	
3.125e+01	2.453e+01	6.208e+01	1.110e+02	1.280e+02	
1.562e+01	2.308e+01	5.830e+01	1.040e+02	1.197e+02	
7.812e+00	2.120e+01	5.330e+01	9.451e+01	1.080e+02	
6.763e+00	2.075e+01	5.209e+01	9.213e+01	1.049e+02	
5.478e+00	2.006e+01	5.019e+01	8.833e+01	9.991e+01	
4.930e+00	1.969e+01	4.918e+01	8.627e+01	9.710e+01	
4.437e+00	1.932e+01	4.813e+01	8.409e+01	9.402e+01	
3.993e+00	1.893e+01	4.703e+01	8.176e+01	9.061e+01	
3.594e+00	1.854e+01	4.590e+01	7.926e+01	
2.911e+00	1.771e+01	4.348e+01	7.354e+01	
1.910e+00	1.592e+01	3.798e+01	
1.547e+00	1.496e+01	3.482e+01	
1.128e+00	1.346e+01	2.924e+01	
1.953e+00	1.602e+01	
9.766e-01	1.276e+01	
4.883e-01	9.240e+00	
2.441e-01	5.837e+00	
1.221e-01	3.122e+00	
6.104e-02	1.576e+00	
3.052e-02	7.902e-01	
1.526e-02	3.955e-01	
7.629e-03	1.979e-01	
3.815e-03	9.895e-02