  Quantum annealers are an alternative approach to quantum computing which make
use of the adiabatic theorem to efficiently find the ground state of a
physically realizable Hamiltonian. Such devices are currently commercially
available and have been successfully applied to several combinatorial and
discrete optimization problems. However, the application of quantum annealers
to problems in chemistry remains a relatively sparse area of research due to
the difficulty in mapping molecular systems to the Ising model Hamiltonian. In
this paper we review two different methods for finding the ground state of
molecular Hamiltonians using Ising model-based quantum annealers. In addition,
we compare the relative effectiveness of each method by calculating the binding
energies, bond lengths, and bond angles of the H+3and H2O molecules and mapping
their potential energy curves. We also assess the resource requirements of each
method by determining the number of qubits and computation time required to
simulate each molecule using various parameter values. While each of these
methods is capable of accurately predicting the ground state properties of
small molecules, we find that they are still outperformed by modern classical
algorithms and that the scaling of the resource requirements remains a
challenge.
