Upper panel: model spectral energy distributions of first moment of specific intensity H_E for pure hydrogen NS atmosphere models with T = 3.1623 MK and logg = 14.3856. The outputs of the codes that use the Thomson approximation for Compton scattering are represented by the blue solid-line (our code) and black dashed-line (MCPHAC code), while the red solid-line represents the output of our code when the full treatment of Compton scattering is used. Lower panel: relative difference between our model results in the Thomson (blue) and full Compton (red) limits compared to those of the MCPHAC code.