Accurate quantum-centric simulations of intermolecular interactions.

Modelling and simulating non-covalent interactions is challenging, as they are inherently weak, dynamic, and system-specific. Common predictive methods often require trading the accuracy for reducing the otherwise cumbersome computational cost. To date, the most accurate approaches, achieving chemical accuracy, rely on quantum mechanical descriptions of non-covalent interactions, which limits their scalability. Whether quantum computing could overcome these limitations is still unclear, as such methods need to be redesigned for quantum hardware. Here, we take the first step in this direction by presenting quantum-centric simulations of non-covalent interactions using a supramolecular approach for binding energy calculations. We use a sample-based quantum diagonalization (SQD) approach to simulate the potential energy surfaces (PES) of the water and methane dimers, featuring hydrogen bond and dispersion interactions, respectively. We benchmark our quantum simulations (27- and 36-qubit circuits) against classical methods, registering deviations within 1.000 kcal/mol from the leading ones. Finally, we test the limits of the quantum methods for capturing dispersion interactions with an experiment on 54 qubits. Beyond reaching state-of-the-art accuracy, our work lays out a framework for electronic structure calculations of non-covalent interactions on quantum hardware.