Figure 1
From: Second order topology in a band engineered Chern insulator
Schematic diagram of the honeycomb lattice. The two sublattices are denoted as A and B. The nearest neighbour vector directions are shown as \(\hat{\delta }_1\), \(\hat{\delta }_2\) and \(\hat{\delta }_3\). The hopping along the direction \(\hat{\delta }_1\) is given by \(t_1\) (shown in green), while it is given by t in the other two directions (shown in black). The second neighbour hoppings are given by dashed lines and have an amplitude \(t_2\).
