Radiative accelerations on Ne are calculated for the atmospheres of main sequence stars with 11 000 \leq \mbox { $T _ { \mathrm { eff } } $ } \leq 15 000 K. This range corresponds to that of the mercury-manganese ( HgMn ) stars .
The calculations take into account neon fine structure as well as shadowing of neon lines using the entire Kurucz line list , bound-bound , bound-free and free-free opacity of H , He and C as well as some NLTE effects .
NLTE effects are found to modify the radiative acceleration by a factor of order 10 ^ { 2 } in the outer atmosphere and are crucial for dm < 10 ^ { -3 } g cm ^ { -2 } .
The dependence of the radiative accelerations on the Ne abundance , effective temperature and gravity is studied .
Radiative accelerations are found to be well below the gravity in the entire range of T _ { \mathrm { eff } } and it is predicted that in stable atmospheres devoid of disturbing motions , Ne should sink and be observed as underabundant .
This agrees with recent observations of low Ne abundances in HgMn stars .