  We study the effect of radiative feedback on accretion onto intermediate mass
black holes (IMBHs) using the hydrodynamical code ZEUS-MP with a radiative
transfer algorithm. In this paper, the first of a series, we assume accretion
from a uniformly dense gas with zero angular momentum and extremely low
metallicity. Our 1D and 2D simulations explore how X-ray and UV radiation
emitted near the black hole regulates the gas supply from large scales. Both 1D
and 2D simulations show similar accretion rate and period between peaks in
accretion, meaning that the hydro-instabilities that develop in 2D simulations
do not affect the mean flow properties. We present a suite of simulations
exploring accretion across a large parameter space, including different
radiative efficiencies and radiation spectra, black hole masses, density and
temperature, $T_\infty$, of the neighboring gas. In agreement with previous
studies we find regular oscillatory behavior of the accretion rate, with duty
cycle $\sim 6%$, mean accretion rate 3% $(T_{\infty}/10^4 {\rm K})^{2.5}$ of
the Bondi rate and peak accretion $\sim 10$ times the mean for $T_{\infty}$
ranging between 3000K and 15000K. We derive parametric formulas for the period
between bursts, the mean accretion rate and the peak luminosity of the bursts
and thus provide a formulation of how feedback regulated accretion operates.
The temperature profile of the hot ionized gas is crucial in determining the
accretion rate, while the period of the bursts is proportional to the mean size
of the Str\"{o}mgren sphere and we find qualitatively different modes of
accretion in the high vs. low density regimes. We also find that softer
spectrum of radiation produces higher mean accretion rate.
