Estimating Phosphorescent Emission Energies in Ir^III Complexes Using Large-Scale Quantum Computing Simulations

Here we calculate T₁ →S₀ transition energies in nine phosphorescent iridium complexes using the iterative qubit coupled cluster (iQCC) method to determine if quantum simulations have any advantages over classical methods. These simulations would require a gate-based quantum computer with at least 72 fully-connected logical qubits. Since such devices do not yet exist, we demonstrate the iQCC method using a purpose-built quantum simulator on classical hardware. The results are compared to a selection of common DFT functionals, ab initio methods, and empirical data. iQCC is found to match the accuracy of the best DFT functionals, but with a better correlation coefficient, demonstrating that it is better at predicting the structure-property relationship. Results indicate that the iQCC method has the required accuracy to design organometallic complexes when deployed on emerging quantum hardware and sets an industrially relevant target for demonstrating quantum advantage.