  We calculate the parameters of the recently-derived many-channel Hubbard
model that is predicted to describe ultracold nonreactive molecules in an
optical lattice, going beyond the approximations used in Do\c{c}aj \textit{et
al.}~[Phys. Rev. Lett. \textbf{116}, 135301 (2016)]. Although those
approximations are expected to capture the qualitative structure of the model
parameters, finer details and quantitative values are less certain. To set
expectations for experiments, whose results depend on the model parameters, we
describe the approximations' regime of validity and the likelihood that
experiments will be in this regime, discuss the impact that the failure of
these approximations would have on the predicted model, and develop theories
going beyond these approximations. Not only is it necessary to know the model
parameters in order to describe experiments, but the connection that we
elucidate between these parameters and the underlying assumptions that are used
to derive them will allow molecule experiments to probe new physics. For
example, transition state theory, which is used across chemistry and chemical
physics, plays a key role in our determination of lattice parameters, thus
connecting its physical assumptions to highly accurate experimental
investigation.
