  Stability and charge states of vacancy in Si$_{29}$ and Si$_{38}$ clusters
have been calculated by non-conventional tight-binding method and molecular
dynamics. Based on the theoretical calculations, it was shown that the vacancy
in pure dimerized clusters is unstable, while in hydrogenated Si$_{29}$H$_{24}$
and Si$_{38}$H$_{30}$ clusters it is stable, but leads to a distortion of its
central part with the transition of symmetry from Td to $C_{3v}$ and a change
in the forbidden gap. The charges of cluster atoms in the presence of a vacancy
are distributed so that all silicon atoms acquire a stable negative charge,
which occurs due to the outflow of electrons of the central atom to the
neighboring spheres.
