  The opportunities afforded by near-term quantum computers to calculate the
ground-state properties of small molecules depend on the structure of the
computational ansatz as well as the errors induced by device noise. Here we
investigate the behavior of these noisy quantum circuits using numerical
simulations to estimate the accuracy and fidelity of the prepared quantum
states relative to the ground truth obtained by conventional means. We
implement several different types of ansatz circuits derived from unitary
coupled cluster theory for the purposes of estimating the ground-state energy
of Sodium Hydride using the variational quantum eigensolver algorithm. We show
how relative error in the energy and the fidelity scale with the levels of
gate-based noise, the inter-molecular configuration, the ansatz circuit depth,
and the parameter optimization methods.
