https://doi.org/10.1140/epjb/e20020032
A study of Peierls instabilities for a two-dimensional t-t' model
Experimentalphysik VI, Universität Augsburg,
86135 Augsburg, Germany
and
Pohl Institute of Solid State Physics, Tongji University,
Shanghai 200092, PR China
Corresponding author: a qingshan.yuan@physik.uni-augsburg.de
Received:
31
July
2001
Published online: 15 February 2002
In this paper we study Peierls instabilities for
a half-filled two-dimensional tight-binding model with
nearest-neighbour hopping t and next nearest-neighbour hopping t'
at zero and finite temperatures. Two dimerization patterns corresponding to
the same phonon vector 
are considered to be realizations of
Peierls states. The effect of imperfect nesting
introduced by t' on the Peierls instability, the properties of the
dimerized ground state, as well as the competition between two
dimerized states for each t' and temperature T, are investigated.
It is found: (i).
The Peierls instability will be frustrated by t' for each of the
dimerized states. The Peierls transition itself,
as well as its suppression by t', may be of second- or first-order.
(ii). When the two dimerized states are considered jointly,
one of them will dominate the other depending on parameters t'
and T. Two successive Peierls transitions, that is, the system passing
from the uniform state to one dimerized state and then to the other may
take place with decrease of temperature.
Implications of our results to real materials are discussed.
PACS: 71.45.Lr – Charge-density-wave systems / 63.20.Kr – Phonon-electron and phonon-phonon interactions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002
