超导体YBa_2Cu_3O_（7－δ）的紧束缚能带计算

THE TIGHT-BINDING BAND STRUCTURE CALCULATIONABOUT YBa_2Cu_3O_(7-δ)SUPERCONDUCTOR

采用ＥＨＴ近似下的紧束缚能带结构计算方法，计算了ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－δ）和ＹＢａ＿２Ｃｕ＿３Ｏ＿６的能带结构。结果表明，穿越超导休ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－δ）费米面的是三条来自Ｃｕ－Ｏ面和Ｃｕ－Ｏ链的能带，半导体ＹＢａ＿２Ｃｕ＿３Ｏ＿６没有来自Ｃｕ－Ｏ链的能带．

We calculated the energy band structures of YBa_2Cu_3O_(7-δ)andYBa_2Cu_3O_6 by performing the tight-binding band structure calculation methodon the basis of EHT approximation.The reesults show that the energy bandsof YBa_2Cu_3O_(7-δ)superconductor crossing tthe Frmi surface are three bands con-sisting of Cu-O planes and Cu-O chains,but none of YBa_2Cu_3O_6 seemicon-ductor consisting of Cu-O chains crosses E_F.