Quantum Computing for Molecules with Increasing Numbers of Electrons

Predicting the properties and reactivity of macromolecules and supramolecular aggregates of biological, pharmacological, and technological interest represents a fundamental challenge in computational chemistry. Despite the development of increasingly efficient algorithms, the computation of systems with a large number of electrons still requires significant computational time, even when using highperformance computing (HPC) systems. This limitation affects both the discovery of new molecular systems and the understanding of complex biochemical mechanisms. Quantum computing, characterized by an increasing number of qubits and progressively reduced error rates, represents a promising paradigm for overcoming these limitations [2]. In particular, quantum algorithms capable of computing molecular properties in reduced time compared to classical HPC approaches are expected to play a key role in the future of computational chemistry. In this work, a Self-Consistent Field (SCF) procedure within the Hartree–Fock approximation [1] is designed to exploit quantum computational capabilities. The proposed approach is applied to molecular systems with increasing numbers of electrons and different geometries, including diatomic molecules and systems with steric numbers ranging from 2 to 6. Ground-state energies obtained through the SCF quantum algorithm are compared with those computed using classical methods. Although the proposed SCF quantum procedure is based on the Hartree–Fock approximation, representing a simplified framework for large systems, this study provides a first step toward understanding both the potential and the current limitations of quantum computing in molecular simulations.