Table 1.

Unit cell structural parameters for each shell.

Shell	1	2	3	4	5	6
${\epsilon }_{eff}$	1.93	1.88	1.84	1.73	1.63	1.54
$r_a$	4.32	4.42	4.56	4.79	5.00	5.22
Number of unit cells	3	16	38	71	113	164
Shell	7	8	9	10	11	12
${\epsilon }_{eff}$	1.42	1.33	1.24	1.18	1.13	1.08
$r_a$	5.46	5.73	6.05	6.24	6.46	6.73
Number of unit cells	227	299	381	473	573	684