Fault-tolerant quantum algorithm for symmetry-adapted perturbation theory

We investigate the calculation of binding energies using the first-order SAPT formalism on a fault-tolerant device, a crucial task in drug discovery. Observable-specific tensor factorization techniques can significantly reduce the algorithm's runtime. We assess the necessary qubit resources, required circuit depth, expected accuracy, and specific steps needed to implement such an algorithm down to the gate level. We identify two significant bottlenecks: the eigenstate reflection subroutine and the 1-norm of the SAPT observable. Future work should consider developing a framework for second-order SAPT energy contributions, studying resource requirements of basis sets with diffuse functions, and exploring alternative techniques. As quantum algorithms become more efficient, this work will be a crucial starting point for drug design and materials research.