Molecular vibrations are relevant to combustion, other gas phase reactions, atmospheric science, and astrochemistry. However, due to anharmonicity and mode coupling effects, simulating vibrational degrees of freedom is often classically intractable. Here we present a set of quantum algorithms for calculating vibrational spectra and linear response properties. For many molecules, the electronic portion of the problem is classically tractable while the vibrational degrees of freedom are not. In such cases, a classical computer may be used to calculate a high-accuracy potential energy surface, which is then used for the quantum simulation. As a proof of principle we emulate a quantum algorithm for carbon monoxide, the isoformyl radical, ozone, and a Fermi resonance model. Finally, we predict that a molecular vibrational problem instance will exhibit quantum advantage before an electronic structure instance, providing ballpark numerical evidence to support this postulate.

Classically prepared potential energy surfaces for quantum simulation of vibrational properties

ACS Spring Meeting 2021

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