Lower bounds for the ground-state energies of the two-dimensional Hubbard andt-Jmodels

1991 ◽  
Vol 43 (16) ◽  
pp. 13743-13746 ◽  
Author(s):  
Roser Valent ◽  
Joachim Stolze ◽  
P. J. Hirschfeld
1990 ◽  
Vol 41 (7) ◽  
pp. 4049-4051 ◽  
Author(s):  
I. C. da Cunha Lima ◽  
M. Fabbri ◽  
A. Ferreira da Silva ◽  
A. Troper

Author(s):  
P. Bérard ◽  
B. Helffer

Given a bounded open set in (or in a Riemannian manifold), and a partition of Ω by k open sets ω j , we consider the quantity , where λ ( ω j ) is the ground state energy of the Dirichlet realization of the Laplacian in ω j . We denote by ℒ k ( Ω ) the infimum of over all k -partitions. A minimal k -partition is a partition that realizes the infimum. Although the analysis of minimal k -partitions is rather standard when k =2 (we find the nodal domains of a second eigenfunction), the analysis for higher values of k becomes non-trivial and quite interesting. Minimal partitions are in particular spectral equipartitions, i.e. the ground state energies λ ( ω j ) are all equal. The purpose of this paper is to revisit various properties of nodal sets, and to explore if they are also true for minimal partitions, or more generally for spectral equipartitions. We prove a lower bound for the length of the boundary set of a partition in the two-dimensional situation. We consider estimates involving the cardinality of the partition.


2012 ◽  
Vol 90 (6) ◽  
pp. 503-513 ◽  
Author(s):  
Vladimír Tichý ◽  
Aleš Antonín Kuběna ◽  
Lubomír Skála

New analytic solutions of the two-dimensional Schrödinger equation with a two-dimensional fourth-order polynomial (i.e., quartic) potential are derived and discussed. The solutions represent the ground state energies and the corresponding wave functions. In general, the obtained results cannot be reduced to two one-dimensional cases.


2018 ◽  
Vol 5 (5) ◽  
Author(s):  
Claudius Hubig

We explore in detail the implementation of arbitrary abelian and non-abelian symmetries in the setting of infinite projected entangled pair states on the two-dimensional square lattice. We observe a large computational speed-up; easily allowing bond dimensions D=10D=10 in the square lattice Heisenberg model at computational effort comparable to calculations at D=6D=6 without symmetries. We also find that implementing an unbroken symmetry does not negatively affect the representative power of the state and leads to identical or improved ground-state energies. Finally, we point out how to use symmetry implementations to detect spontaneous symmetry breaking.


2005 ◽  
Vol 25 (3) ◽  
pp. 379-385
Author(s):  
G. P. Kamuntavičius ◽  
D. Germanas ◽  
R. K. Kalinauskas ◽  
S. Mickevičius ◽  
R. Žemaičinienė

1969 ◽  
Vol 13 (2) ◽  
pp. 155-158
Author(s):  
M. Bersohn ◽  
M. Glicksohn ◽  
J. Stewart

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