1999/04/28 by Yoshihiro Asai, H. Katagiri, Hideki Katagiri · 6 citations
Physics and Astronomy · #Ab initio #Advanced Condensed Matter Physics #Atomic physics #Band gap #Cluster (spacecraft) #Condensed matter physics #Coupled cluster #Electron #Electronic correlation #Excitation #Hubbard model #Molecule #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Superconductivity #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.60.r13946
published in Physical review. B, Condensed matter 60(20), R13946-R13949 (American Physical Society) · RevTeX3.0, 4 pages, 4 figures
arxiv created 1999/04/28 · openalex publication_date 1999/11/15 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We have studied electron correlations in the doped two-dimensional (2D) Hubbard model by using the coupled-cluster method (CCM) to investigate whether or not the method can be applied to correct the independent particle approximations actually used in ab initio band calculations. The double excitation version of the CCM, implemented using the approximate coupled pair (ACP) method, accounts for most of the correlation energies of the 2D Hubbard model in the weak (U/t\ensuremath≃1) and the intermediate U/t regions (U/t\ensuremath≃4). The error in this case is always less than 1%. The ACP approximation gets less accurate for large U/t (U/t\ensuremath≃8) and near half-filling. Further incorporation of electron correlation effects is necessary in this region. The accuracy depends neither on the system size, nor the gap between the lowest unoccupied level and the highest occupied level in the finite size effect. Hence, the CCM may be favorably applied to ab initio band calculations on metals as well as semiconductors and insulators.