H.P. Paudel, B. Avramidis, D. Alfonso, K.D. Jordan, Y. Duan
National Energy Technology Laboratory,
Keywords: quantum computing, quantum algorithms, qubits
Summary:Use of quantum simulators like IBM’s Qiskit allow us to perform quantum mechanical calculations on classical computers. Quantum simulators have already proven to be useful in simulating simple molecular systems. In this study, we provide recent development on the quantum computing and simulation for the molecular systems that are useful for energy applications. Examples using quantum simulation are presented using Lithium hydride (LiH) and its ionic systems. These systems are important for Lithium-ion battery applications. Ground state properties of LiH complexes, including their single-charged ions, are considered using Variational Quantum Eigensolver (VQE) as implemented in IBM’s Qiskit platform and the results are compared to those computed using traditional computational quantum chemistry software. Results obtained using the VQE unitary coupled cluster with single and double excitations (UCCSD) in Qiskit are compared to those obtained using similar Gaussian and PySCF type calculations. Computed ground state energies, electron affinities, ionization potentials and dipole moments are considered when analyzing possible discrepancies using quantum and traditional simulation methods. Overall, results produced using VQE and chosen ansatz agree with their traditional quantum chemistry counterparts. Our results for total energies and dipole moments for LiH are consistent with experimental and available VQE results published in the literatures. These results may be useful for further benchmarking the quantum hardware and developing the quantum algorithm for chemistry applications.