\[fig:bs\](b)) is in rough agreement with the experimental observations at low frequencies and successfully reproduces a peak at 950 cm$^{-1}$ (green arrows) although the predicted amplitude is much larger. However, as one can see, the calculated conductivity is significantly higher than the experimental one almost all throughout the frequency range. The origin and significance of this peak will be discussed further below.

The more striking feature is perhaps the almost complete absence of a large peak close to 200 cm$^{-1}$ (red arrows) in the calculated optical conductivity spectra which might be indicative of some deeper inconsistencies. As the band structure in figure \[fig:bs\](a) does not include the canting of the Mn$^{2+}$ moments that is believed to be necessary for the magnetic WSM phase, a next obvious step is to include that in the DFT calculations.

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     ![Band structure calculated along symmetry lines for a canting of (a) 5$^{\circ}$ and (b) 10$^{\circ}$ from the c-axis. The solid and dashed lines of the same colors represent the bands that were degenerate without canting. (c) Comparison of the calculated optical conductivity for different canting with experiment[]{data-label="fig:cant"}](S1_cant.png "fig:"){width="48.00000%"}

Figure \[fig:cant\](a) and \[fig:cant\](b) shows the band structure along (001) for a canting of 5$^{\circ}$ 