  We present a practical workflow to compute the potential energy curve of the
hydrogen molecule on near intermediate-scale quantum (NISQ) devices. The
proposed approach uses an extrapolation scheme to deliver, with only few
qubits, full configuration interaction results close to the basis-set limit. We
show that despite the limitations imposed by the noisy nature of simulated
quantum hardware, it is possible to recover realistic electronic correlation
values, if we also estimate expectation values of the Hartree-Fock ground state
energy. Using two models of noisy quantum experiments, we evaluate the
performance of a scheme that requires at most a double-zeta basis set (3-21G,
in this case) and compare with the most accurate Born-Oppenheimer potential
energy curves available in the literature. Our flexible approach is implemented
using simple variational ansatzes combined with straightforward mitigation
techniques and thus we expect it to be also suitable for other energy
estimation quantum schemes.
