2020/06/26 by Kai Guther, Robert J. Anderson, Nick S. Blunt +24 · 99 citations
Materials Science · Physics and Astronomy · #Ab initio #Advanced Chemical Physics Studies #Basis (linear algebra) #Density matrix #Excited state #Full configuration interaction #Hamiltonian (control theory) #Interface (matter) #Machine Learning in Materials Science #Monte Carlo method #Quantum #Spectroscopy and Quantum Chemical Studies #physics.comp-ph
paper · pdf · doi:10.1063/5.0005754
published in The Journal of Chemical Physics 153(3), 034107 (American Institute of Physics) · 68 pages, 8 figures. To be published in the Journal of Chemical Physics, full supplementary files are to be published together with the article
arxiv created 2020/06/26 · openalex created_date 2020/07/02 · openalex publication_date 2020/07/16 · arxiv updated 2020/08/26 · openalex updated_date 2026/08/05
We present NECI, a state-of-the-art implementation of the Full Configuration Interaction Quantum Monte Carlo (FCIQMC) algorithm, a method based on a stochastic application of the Hamiltonian matrix on a sparse sampling of the wave function. The program utilizes a very powerful parallelization and scales efficiently to more than 24 000 central processing unit cores. In this paper, we describe the core functionalities of NECI and its recent developments. This includes the capabilities to calculate ground and excited state energies, properties via the one- and two-body reduced density matrices, as well as spectral and Green's functions for ab initio and model systems. A number of enhancements of the bare FCIQMC algorithm are available within NECI, allowing us to use a partially deterministic formulation of the algorithm, working in a spin-adapted basis or supporting transcorrelated Hamiltonians. NECI supports the FCIDUMP file format for integrals, supplying a convenient interface to numerous quantum chemistry programs, and it is licensed under GPL-3.0.