Asthana, AyushKumar, AshutoshAbraham, VibinGrimsley, HarperZhang, YuCincio, LukaszTretiak, SergeiDub, Pavel A.Economou, Sophia E.Barnes, Edwin FlemingMayhall, Nicholas J.2023-03-282023-03-282023-01-27http://hdl.handle.net/10919/114195Near-term quantum computers are expected to facilitate material and chemical research through accurate molecular simulations. Several developments have already shown that accurate ground-state energies for small molecules can be evaluated on present-day quantum devices. Although electronically excited states play a vital role in chemical processes and applications, the search for a reliable and practical approach for routine excited-state calculations on near-term quantum devices is ongoing. Inspired by excited-state methods developed for the unitary coupled-cluster theory in quantum chemistry, we present an equation-of-motion-based method to compute excitation energies following the variational quantum eigensolver algorithm for ground-state calculations on a quantum computer. We perform numerical simulations on H-2, H-4, H2O, and LiH molecules to test our quantum self-consistent equation-of-motion (q-sc-EOM) method and compare it to other current state-of-the-art methods. q-sc-EOM makes use of self-consistent operators to satisfy the vacuum annihilation condition, a critical property for accurate calculations. It provides real and size-intensive energy differences corresponding to vertical excitation energies, ionization potentials and electron affinities. We also find that q-sc-EOM is more suitable for implementation on NISQ devices as it is expected to be more resilient to noise compared with the currently available methods.application/pdfenCreative Commons Attribution 4.0 InternationalCoupled-cluster methodexcited-statepropagatorconstructionchemistryArticle - Refereedhttps://doi.org/10.1039/d2sc05371c368738392041-6539