  We study possible quantum states of two correlated electrons in a
two-dimensional crystal and find a metastable energy band of the electron pair
between the two lowest single-electron bands. These metastable states result
from the interplay of electron correlations and the strength of the crystal
potential. The two paired electrons are bound in the same unit cell in relative
coordinates with an average distance between them about one third of the
crystal period. Furthermore, we show how such electron-pairs can be stabilized
in a many-electron system.

Strongly Correlated Electrons