In the realm of quantum chemistry and energy research, a significant advancement has been made by Kenji Sugisaki, a researcher at the University of Tokyo. This development could potentially revolutionize how we approach large-scale quantum chemical calculations, which are crucial for understanding and improving energy-related processes.
The research focuses on the quantum-selected configuration interaction (QSCI) method, a promising approach for performing complex quantum chemical calculations on current quantum hardware. However, the initial implementation of QSCI lacked size consistency, a vital property for accurately calculating intermolecular interaction energies using the supramolecular approach. Size consistency ensures that the energy of a system scales correctly with its size, which is essential for studying large molecules and molecular interactions.
Sugisaki’s team has developed a size-consistent implementation of QSCI. This was achieved by sampling Slater determinants for the dimer in a localized molecular orbital basis, constructing subspaces for the monomers and dimer, and augmenting the dimer subspace with additional determinants to ensure size consistency. This method, termed Hamiltonian simulation-based QSCI (HSB-QSCI), was successfully applied to various molecular systems, including 4H/8H clusters, the FH dimer, and the FH–H2O system. The results demonstrated that the approach numerically satisfies size consistency and reproduces complete active space-configuration interaction (CAS-CI) values with high accuracy, showing errors below 0.04 kcal mol⁻¹.
The practical applications of this research for the energy sector are substantial. Accurate calculations of intermolecular interactions are crucial for understanding and designing processes involved in energy storage, conversion, and catalysis. For instance, the study of hydrogen-bonded systems, like the FH dimer and FH–H2O, can provide insights into hydrogen storage and fuel cell technologies. Moreover, the ability to perform large-scale quantum chemical calculations on current quantum hardware brings us closer to the practical realization of quantum computing in the energy industry.
This research was published in the Journal of Chemical Theory and Computation, a leading journal in the field of theoretical and computational chemistry. The findings represent a significant step forward in the development of quantum chemical methods and their applications in the energy sector. As quantum computing technology continues to advance, methods like HSB-QSCI will become increasingly important for addressing the complex challenges faced by the energy industry.
This article is based on research available at arXiv.