Figure 2.

The total computing time for calculating a series of (E) for all relevant modes in - 1 ≤ E ≤ 1 eV with 0.001 eV spacing using analytic (○) and iterative (Δ) methods in the TBDE model for different GNR width. The iterative method takes about 40 × longer than that of analytic method. Included for comparison is the total time to calculate the corresponding surface Green's functions calculated using iterative method in the TB-π model (◊).