Extracting Infinite System Properties from Finite Size Clusters: 'Phase Randomization/Boundary Condition Averaging'
Abstract
When electron-electron correlations are important, it is often necessary fo use 'exact' numerical methods, such as Lanczoes diagonalization, to study the full many-body Hamiltonian. Unfortunately, such exact diagonalization methods are restricted to small system sizes. We show that if the Hubbard U term is replaced by a 'periodic Hubbard' term, the full many body Hamiltonian may be exactly solved, even for very large systems, though for low fillings. However, for half-filled systems and large U this approach is not only no longer exact, it no longer improved extrapolation of larger systems. We discuss how generalized 'randomized variable averaging' (RAV) or 'phase randomization' schemes can be reliably employed to improve extrapolation of large system sizes in this regime. This general approach can be combined with any many-body method and is thus of broad interest and applicability.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1993
- Accession Number
- ADA265554
Entities
People
- D. K. Campbell
- E. Y. Loh Jr.
- J. T. Gammel
Organizations
- Naval Command, Control and Ocean Surveillance Center