ELECTRONIC STATES OF CU IN CUPRATE SUPERCONDUCTORS - ATOMIC MODEL

The electronic states of Cu in crystals were investigated in the frame work of the Slater model of neutral atoms in crystals. It was shown th at the closeness of divalent 3d(9)4s(2) and monovalent 3d(10)4s states of Cu and the strong dependence of their mutual arrangement on the cr ystal field strength is the distinctive feature of Cu among transition metal elements and other neighbors in Periodic Table. These Cu States show the tendency to cross in Cu-O planes of cuprate superconductors, when superconducting composition is approached.