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We investigate the Landau parameters for the instabilities in spin and chargechannels in the nondegenerate extended Hubbard model with intersite Coulomb andexchange interactions. To this aim we use the spin rotationally invariant slaveboson approach and we determine the necessary inverse propagator matrix. Theanalytically derived spin Landau parameter $F_0^a$ for the half filled banduncovers the intrinsic instability of the nondegenerate Hubbard model towardsferromagnetism --- negative intersite exchange interaction triggers aferromagnetic instability at half filling before the metal-insulatortransition, indicated by the divergence of the magnetic susceptibility at$F_0^a=-1$. This result is general and the instability occurs in the stronglycorrelated metallic regime for any lattice, in three or two dimensions. Next asan illustrative example we present numerical results obtained for the cubiclattice with nearest neighbor exchange $J$ and Coulomb $V$ elements andarbitrary electron density. One finds that the range of small doping near halffilling is the most unstable one towards spin polarization, but only in thecase of ferromagnetic intersite exchange $J<0$. Charge Landau parameter $F_0^s$is lowered near half filling by increasing $U$ when the intersite Coulombinteraction $V$ is attractive, but in contrast to $F_0^a$ at $J<0$ it requiresan attraction beyond a critical value $V_c$ to generate the divergence of thecharge susceptibility at $F_0^s=-1$ in the metallic phase. This instability wasfound for a broad range of electronic filling away from half filling formoderate attraction.

Fermi-liquid Landau parameters for a nondegenerate band: Spin and charge instabilities in the extended Hubbard model