  The generalized boundary conditions for the envelope wave function that take
into account the real structure of an interface were used to investigate the
hole spectrum of the semiconductor quantum dot embedded in an insulator matrix.
An essential influence of the interface levels, which could exist at the top of
the valence band, on the hole spectrum has been demonstrated. It is found that
usually applied boundary conditions, wherein all components of the envelope
wave function vanish at the interface, can be used only in the absence of the
interface levels close to the band edge.
