Fig. 3. Comparison of experimental QPI patterns with T-matrix calculations.

a−d QPI patterns at negative energy with decreasing energy. The panels on the left show the comparison between the experimental data and the T-matrix calculation of the QPI for the full bulk electronic structure. For each energy, the ratio p_z/p_xy of the orbital contributions required to describe the experimental data is indicated. The panels on the right show the QPI patterns originating from sulfur {p_x, p_y} (left) and p_z states (right). e−h QPI patterns at positive energies with increasing energy with the orbital contributions from the Pb p-orbitals. Left and right panels as for (a−d). Near the band edge, disconnected QPI patterns are observed as expected for the top and bottom of the valence and conduction bands, respectively, which join as the absolute energy increases. For all panels, the q vector spans the reciprocal space from $\left(\frac{-2\pi }{a},\frac{-2\pi }{a}\right)$ to $\left(\frac{2\pi }{a},\frac{2\pi }{a}\right)$, where a is the lateral lattice parameter of the tetragonal supercell shown in Fig. 1b.