C. BORGS, J. J\c EDRZEJEWSKI, R. KOTECKY
THE STAGGERED CHARGE-ORDER PHASE OF THE EXTENDED HUBBARD MODEL 
IN THE ATOMIC LIMIT
(54K, LaTeX)

ABSTRACT.  We study the phase diagram of the extended Hubbard model in the atomic limit. At zero temperature, the phase diagram decomposes into six regions: three with homogeneous phases (characterized by particle densities $\rho=0$, $1$, and $2$ and staggered charge density $\Delta=0$) and three
with staggered phases (characterized by the densities  $\rho={1\over 2}$, $1$, and ${3\over 2}$ and staggered densities $|\Delta|={1\over 2}$, $1$,  and ${1\over 2}$). Here we use Pirogov-Sinai theory to analyze the details of the  phase diagram of this model at low temperatures. In particular, we show that for any sufficiently low nonzero temperature the three staggered
regions merge into one staggered region $S$, without any phase transitions (analytic free energy and staggered order parameter $\Delta$) within $S$.