2 research outputs found
On the lowest energy excitations of one-dimensional strongly correlated electrons
It is proven that the lowest excitations of one-dimensional
half-integer spin generalized Heisenberg models and half-filled extended
Hubbard models are -periodic functions. For Hubbard models at fractional
fillings , where , and is
the number of electrons per unit cell. Moreover, if one of the ground states of
the system is magnetic in the thermodynamic limit, then for
any , so the spectrum is gapless at any wave vector. The last statement is
true for any integer or half-integer value of the spin.Comment: 6 Pages, Revtex, final versio