Top panel: differences between the excitation temperature T_ex and the electron temperature T_e calculated for the Si i 10 827 Å line along the surface line iy = 10 in the 3D snapshot model with ⟨ | B_Z | ⟩ = 80 G. The T_ex and the T_e values are determined at the heights H₀(LTE) where the LTE optical depth at the line center τ₀(LTE) = 1. Curves of different colors indicate results obtained using three silicon atomic models. Arrows show the grid points ix = 28 (the granule) and ix = 59 (the intergranule). Bottom panel: the differences ΔT_ex in the excitation temperature along the same surface line iy = 10 obtained by using different atomic models of the silicon atom. Dashed curve: the ΔT_ex values found by comparing the excitation temperatures computed from the simplest Si i model with six bb transitions and the Si i working model with 605 bb transitions. Dashed-dotted green curve: the ΔT_ex values obtained by comparing the simplest Si i model and the comprehensive Si i + Si ii model with 4708 bb transitions.