Coarse-grained intermolecular interactions on quantum processors

Variational quantum algorithms (VQAs) are increasingly being applied in simulations of strongly bound (covalently bonded) systems using full molecular orbital basis representations. The application computers to the weakly intermolecular and noncovalently bonded regime, however, has remained largely unexplored. In this work, we develop a coarse-grained representation electronic response that is ideally suited for determining ground state interacting molecules VQA. We require qubit numbers grow linearly with number derive scaling behavior circuits measurements required, which compare favorably traditional variational eigensolver methods. demonstrate our method on IBM superconducting processors show its capability resolve dispersion energy as function separation pair nonpolar molecules---thereby establishing means by can model Van der Waals interactions directly from zero-point fluctuations. Within approximation, conclude current-generation hardware capable probing energies but nevertheless chemically ubiquitous biologically important regime. Finally, perform experiments simulated real three, four, five oscillators well anharmonic onsite binding potentials; consequences latter unexamined large classical computational methods be incorporated here low overhead.