QUASI-PARTICLE SPECTRAL WEIGHT IN THE 2-DIMENSIONAL ELECTRON-GAS

The quasi-particle spectral weight at the Fermi level (Z(F)) in the two-dimensional (2D) electron gas is determined as a function of density. A model local field correction factor (G(q)) possessing the correct features both in the small and large q limits is introduced and used to calculate the Z(F), by evaluating the electron self-energy within the GW approximation. It is found that the Z(F) calculated using the present G(q) is smaller than the one calculated using the Hubbard G(q) implying that the correlation interaction makes the system more localized. Our result also indicates that high T(c) superconductors, if described by a 2D electron gas system, will exhibit a small but nonzero (approximately 0.2) quasi-particle spectral weight at the Fermi level.