  We present a detailed NLTE analysis of 39 MnI lines in the solar spectrum.
The influence of NLTE effects on the line formation and element abundance is
investigated. Our goal is the derivation of solar log gfe values for manganese
lines, which will later be used in differential abundance analysis of
metal-poor stars. The method of spectrum synthesis is employed, which is based
on a solar model atmosphere with initially specified element abundances. A
manganese abundance of 5.47 dex is used with the theoretical line-blanketed
model atmosphere. Statistical equilibrium calculations are carried out for the
model atom, which comprises 245 and 213 levels for MnI and MnII, respectively.
Photoionization cross-sections are assumed hydrogenic. For line synthesis van
der Waals broadening is calculated according to Anstee & O'Mara's formalism. It
is shown that hyperfine structure of the Mn lines also has strong broadening
effects, and that manganese is prone to NLTE effects in the solar atmosphere.
The nature of the NLTE effects and the validity of the LTE approach are
discussed in detail. The role of photoionization and collisional interaction is
investigated.
