Properties of the Ground State

Tim Joachim Zuehlsdorff

Jiang Zhong

The properties of ground state in a simple photon phonon interactive model are studied by using a new coherent state function. The energy and wave concise approach, and some discussions on properties of ground state are given.

Andreas Klümper, Andreas Schadschneider, J. Zittartz

We have found the exact ground state for a large class of antiferromagnetic spin-1 models with nearest-neighbour interactions on a linear chain. All ground-state properties can be calculated. The ground state is determined as a matrix product of individual site states and has the properties of the Haldane scenario.

Ilexa Yardley

O. M. Braun, Yuri S. Kivshar

Akihisa Koga, Hiroyuki Tomishige, Joji Nasu

We study ground-state and thermodynamic properties of an $S=1$ Kitaev model. We first clarify the existence of global parity symmetry in addition to the local symmetry on each plaquette, which enables us to perform the large scale calculations up to 24 sites. It is found that the ground state should be singlet and its energy is estimated as $E/N\sim -0.65J$, where $J$ is the Kitaev exchange coupling. We find that a lowest excited state belongs to the same subspace as the ground state and the gap monotonically decreases with increasing system size, which suggests that the ground state of the $S=1$ Kitaev model is gapless. By means of the thermal pure quantum states, we clarify finite temperature properties characteristic of the Kitaev models with $S\le 2$.