13 citations · 23 across the 4 of their papers we have counts for
5 papers
Correlation and confinement induced itinerant ferromagnetism in chain structures
Reka Trencsenyi, Endre Kovacs, Zsolt Gulacsi
Using a positive semidefinite operator technique one deduces exact ground states for a zig-zag hexagon chain described by a non-integrable Hubbard model with on-site repulsion. Fla…
Exact ground states for the four-electron problem in a two-dimensional finite Hubbard square system
Endre Kovacs, Zsolt Gulacsi
We present exact explicit analytical results describing the exact ground state of four electrons in a two dimensional square Hubbard cluster containing 16 sites taken with periodic…
Exact ground states for the four-electron problem in a Hubbard ladder
Endre Kovacs, Zsolt Gulacsi
The exact ground state of four electrons in an arbitrary large two leg Hubbard ladder is deduced from nine analytic and explicit linear equations. The used procedure is described,…
Four electrons in a two-leg Hubbard ladder: exact ground states
Endre Kovacs, Zsolt Gulacsi
In the case of a two-leg Hubbard ladder we present a procedure which allows the exact deduction of the ground state for the four particle problem in arbitrary large lattice system,…
An extension of a characterization of the automorphisms of Hilbert space effect algebras
Lajos Molnar, Endre Kovacs
The aim of this paper is to show that if an order preserving bijective transformation of the Hilbert space effect algebra also preserves the probability with respect to a fixed pai…