  In a recent paper Hao et al. [Phys. Rev. B 80, 035329 (2009)] reported
variational calculations of energy spectrum for shallow hydrogenic donor in the
structure of semiconductor/insulator/metal with a new type of trial wave
function. They also performed calculations for semiconductor/insulator system
and found that their method gives energy values lower than those obtained by
MacMillen and Landman [Phys. Rev. B 29, 4524 (1984)]. As follows from these
results MacMillen and Landman have got much larger errors in energy values than
they expected. However we confirm that the theoretical approach suggested by
MacMillen and Landman gives rather accurate energy values for the system of
hydrogenic donor near the interface between semiconductor and insulator.
