D4.4 Completion of first software suite (Open source software)
Arseny Kovyrshin, Giorgio Silvi, Bruno Chagas, Goar Sánchez‐Sanz, Venkatesh Kannan · Zenodo (CERN European Organization for Nuclear Research) · 2022
Here, we present an overview of the quantum computing computational package for quantum chemistry. It is comprised of the following two repositories: Automatic fragmentation tool (Chagas & Sànchez, 2022) Variational algorithms suite (Kovyrshin & Silvi, 2021) The first repository contains molecule analysis and fragmentation tools based on graph theory. The second con-tains variational Hamiltonian ansatze adapted to chemical systems is used for state preparation. Equipped with the variational algorithms for imaginary- and real-time evolution, the package can optimize and propagate in time wave functions for chemical systems. As the Pre-Born-Oppenheimer molecular structure is implemented, one can describe nuclear quantum effects. In this report, we first give an introduction of the features of the each repository. Aferwards we explain briefly the theory behind the methods. Later, we show use cases for the developed methods on small chemical systems such as lithium hydride and hydrogen molecules. Specifically, the real- and imaginary-time evolutions have been proven to work correctly and efficiently. The Pre-Born-Oppenheimer scheme delivers results in agreement with the reference. Furthermore, it is shown that the variational Hamiltonian ansatz may approximate wave functions more efficiently than traditional variational ansatzes. For more information about the code and for a documentation we refer the reader to the respective repositories (Chagas & Sànchez, 2022; Kovyrshin & Silvi, 2021).