Figure 4: The parameters of the k·p Hamiltonian for the 1SL Bi₂Te₂I₂ film.

The parameters of the 4-band (a,c) and 8-band (b,d) Hamiltonian are shown as a function of the expansion of the van-der-Waals spacing, which is given in percents of the bulk value. In graph (b), the parity of the respective LDA wave functions is also shown.