  We show that two added, excess electrons with opposite spins in
one-dimensional crystal lattices with quartic anharmonicity may form a
bisolectron, which is a localized bound state of the paired electrons to a
soliton-like lattice deformation. It is also shown that when the Coulomb
repulsion is included, the wave function of the bisolectron has two maxima, and
such a state is stable in lattices with strong enough electron-(phonon/soliton)
lattice coupling. Furthermore the energy of the bisolectron is shown to be
lower than the energy of the state with two separate, independent electrons, as
even with account of the Coulomb repulsion the bisolectron binding energy is
positive
