Top panel: the shift of the height of formation ΔH₀(NLTE) = H₀(NLTE)−H₀(LTE) of the Si i 10 827 Å line center (Δλ = 0) along the surface line iy = 10 in the 3D snapshot with ⟨ | B_Z | ⟩ = 80 G caused by the line opacity change due to the NLTE effects. Curves of different colours indicate results obtained using three different models of the silicon atom. Arrows mark the grid points ix = 28 (the granule) and ix = 59 (the intergranule). Bottom panel: the differences ΔH between the NLTE heights H₀(NLTE) of formation of the line center along the same surface line iy = 10 produced by using three different silicon model atoms. Dashed curve: the ΔH values found by comparing the H₀(NLTE) values for the simplest Si i model with six bb transitions and for the Si i working model with 605 bb transitions. Dash-dotted green curve: the ΔH values obtained by using the simplest Si i model and the comprehensive one with 4708 bb transitions.