  Momentum-dependent local ansatz (MLA) wavefunction approach to correlated
electrons in solids has been extended to the quasiparticle excited states on
the basis of the Fermi liquid picture. The quasiparticle energy is derived from
the MLA-base excited state wavefunction within the single-site approximation.
The quasiparticle weight and quasiparticle energy have been calculated for the
Hubbard model on the hypercubic lattice in infinite dimensions as well as the
simple cubic lattice. By comparing the numerical results with the
single-particle excitation spectra obtained by the Green function method, it is
shown that the MLA excited wavefunctions describe well the quasiparticle states
in the weak and intermediate Coulomb interaction regime in the high dimensional
system.

Strongly Correlated Electrons