  The thermodynamic properties of dipolar spin ice on square, honeycomb and
shakti lattices in the long-range and short-range dipole interaction models are
studied. Exact solutions for the density of states, temperature dependencies of
heat capacity, and entropy are obtained for these lattices with a finite number
of point dipoles by means of complete enumeration. The magnetic susceptibility
and average size of the largest low-energy cluster are calculated for square
spin ice by means of Wang-Landau and Metropolis methods. We show that the
long-range interaction leads to a blurring of the energy spectrum for all
considered lattices. The inclusion of the long-range interaction leads to a
significant change in the thermodynamic behaviour. An additional peak of heat
capacity appears in the case of the honeycomb lattice. The critical temperature
shifts in the direction of low or high temperatures; the direction depends on
the lattice geometry. The critical temperature of the phase transition of
square spin ice in the long-range model with frustrated ground states is
obtained with the Wang-Landau and Metropolis methods independently.
