LSD Calculation of Electronic Structure of High T_c Superconductor: La–Sr–Cu–O Systems

Spin-polarized band structures of high Tc La–Sr–Cu–O compounds are first calculated by a self-consistent nonlocal pseudopotential method in the local spin density (LSD) functional formalism where the basis set is expanded in terms of gaussian orbitals. The calculated results show that a spin polarization occurs in this system. The obtained difference of the total numbers of the upper and lower spins in this calculation is 0.4. This result suggests that the electron-electron interactions in the conduction bands are important for high Tc superconductivity, but no so strong compared with the concept of the ordinary Hubbard model.