氧含量对YBa_2Cu_3O_(7-δ)能级结构的影响

Effect of Oxygen Content on the Energy Level of YBa_2Cu_3O_(7-δ) Superconductors

用Gaussian-03软件中的密度泛函理论(DFT)BLYP/LanL2MB方法系统计算了YBa2Cu3O7-δ(0≤δ≤1)不同氧含量时的能级结构,特别是费米面附近的能级特征。根据计算结果发现氧含量对YBa2Cu3O7-δ深层能级影响较小,对最高占据态附近的能级影响较大,且随着氧含量的增加,最高占据态能级降低。计算结果能很好地解释Tc随氧含量变化的实验规律,从一个侧面说明了氧含量在YBCO超导体中的作用机理。

Electronic structures were calculated for a series of YBa2Cu3O7-δ （0≤δ≤ 1） in different oxygen concentrations by the density function theory （DFT） at BLYP/LanL2MB level by using Gaussian-03 packages. Attentions have been paid especially to the energy level feature near the Fermi level. The results show that the oxygen concentration would greatly influence the energy levels around the highest occupied orbital, but the inner energy levels a little. When the oxygen concentration increases, the energy level of the highest occupied orbit decreases and the state density increases. This is consistent with the experimental observation of Tc values at different oxygen concentrstions.