A SCF Crystal field consisted of point charges with convergency and a Hartree-Fock surface potential has been proposed for cluster ab initio calculations modeling solid materials. The arithmetic of the point charges integral is similar to that of nuclear attraction potential. The integral of the HF surface potential is obtained using point group symmetry. The charges consistency for both within and outside the cluster is reached in iteration process. The calculations of high temperature superconductor YBa2Cu3O7 are performed using the model and a few of new results is obtained.

Key words: COPPER OXIDE, YTTRIUM OXIDE, AB INITIO CALCULATION, SUPERCONDUCTORS, SELF-CONSISTENT FIELD, BARIUM OXIDE