  This study shows that the statistical equilibrium of Si II in the atmosphere
of a B3 IV type star iota Her is extremely sensitive to a variation in
photoionization cross-sections for the Si II levels. The difference in
abundances derived from absorption lines of Si II between applying the data
from two equal accuracy sources, namely, the Opacity Project (OP) and the NORAD
database, amounts to 0.18 dex, on average. Using the hydrogenic approximation
for photoionization cross-sections, we obtain the departure coefficients for
the Si II \eu{4s}{2}{S}{}{} level, the source function for Si II 6371 A, and
the abundance derived from this line, which are very similar to the
corresponding values computed by Takeda (2022). We suppose that close-to-solar
abundance obtained by Takeda (2022) from Si II 6371 A in iota Her is due to
using the hydrogenic photoionization cross-sections for the Si II levels.
However, emission lines of Si II observed in iota Her can only be reproduced
with the OP photoionization cross-sections. Photoionization cross-sections for
the Si II levels need further improvements.
