Momentum-Dependent Local Ansatz Approach to the Quasiparticle States

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.