Bridging Quantum Mechanics and Biology at the Million-Atom Scale

Quantum-mechanical simulations provide the most fundamental description of matter, yet their computational cost has limited applications to systems containing at most thousands of atoms. Here, we present an all-electron quantum-mechanical framework that extends the accessible system size to the multimillion-atom regime. By combining an algorithmically optimized Hartree-Fock formalism with divide-and-conquer, our new approach efficiently handles structures containing millions of atoms with subatomic resolution. We demonstrate this approach on very large biological systems, including a complete bacteriophage in water, totalling over 150 million electrons, representing, to our knowledge, the largest quantum-mechanical calculation performed to date. Our framework allows computing spectral data for DNA and drugs and enables protein structure assessments in strong agreement with structure evaluations by AlphaFold. This approach opens new avenues in quantum physics, structural biology, spectroscopy, bioinformatics, medicine, and materials science.