Chapter One - Electronic Structure Calculations for Antiferromagnetism of Cuprates Using SIWB Method for Anions in DV and a Density Functional Theory Confirming from Finite Element Method

Describing antiferromagnetism in density functional theory (DFT) had been an unsolved problem since the 1930s until recently. This chapter containing a significant review reports the SIWB (surrounding or solid Coulomb potential-induced well for basis set) method for the antiferromagnetic state derivation in copper oxides. SIWB uses the discrete variational (DV) method, which employs numerical atomic orbital basis functions in a DFT. Within Cu oxides, O2- is stable, whereas in a vacuum only the O- state is experimentally observed, although O2- is not observed in a vacuum. DV adds a well potential to the electron potential to generate an anion basis set without predicting the radius and depth of the well. The present SIWB method theoretically determines the radius and depth of the well for an anion (negative ion), and this derived well is shallower than the conventional well, leading to antiferromagnetism. We confirm the effectiveness of SIWB approach using the finite element method.