Variational optimization of the 2DM: approaching three-index accuracy using extended cluster constraints
| Autor: | Dimitri Van Neck, Brecht Verstichel, Ward Poelmans, Sebastian Wouters, Stijn De Baerdemacker |
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| Rok vydání: | 2014 |
| Předmět: |
Quantum Physics
Strongly Correlated Electrons (cond-mat.str-el) Hubbard model FOS: Physical sciences Condensed Matter Physics Variational optimization Electronic Optical and Magnetic Materials Condensed Matter - Strongly Correlated Electrons Lattice (order) Homogeneous space Cluster (physics) Applied mathematics Fraction (mathematics) Reduced density matrix Quantum Physics (quant-ph) Mathematics |
| Zdroj: | The European Physical Journal B. 87 |
| ISSN: | 1434-6036 1434-6028 |
| Popis: | The reduced density matrix is variationally optimized for the two-dimensional Hubbard model. Exploiting all symmetries present in the system, we have been able to study $6\times6$ lattices at various fillings and different values for the on-site repulsion, using the highly accurate but computationally expensive three-index conditions. To reduce the computational cost we study the performance of imposing the three-index constraints on local clusters of $2\times2$ and $3\times3$ sites. We subsequently derive new constraints which extend these cluster constraints to incorporate the open-system nature of a cluster on a larger lattice. The feasibility of implementing these new constraints is demonstrated by performing a proof-of-principle calculation on the $6\times6$ lattice. It is shown that a large portion of the three-index result can be recovered using these extended cluster constraints, at a fraction of the computational cost. 26 pages, 10 figures, published version |
| Databáze: | OpenAIRE |
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