中文摘要：

用电子密度泛函方法（DFT）对YBa2Cu3O7晶胞39个原子模型系统计算了其能隙随温度的变化规律，并在能隙计算基础上，应用电子比热的双极化和热激发的极化子模型计算了电子比热及其系数随温度的变化关系。计算结果表明：超导能隙在超导临界温度点93K附近有不为零的极小值：能隙曲线中的几个转折温度点依次分别与Tc，T^＊和T^0相对应；在Tc～T^＊温度范围，超导态消失，但有反铁磁自旋相干引起的自旋能隙的存在；在T^＊～T^0温度范围，有周期性条纹相产生的电子密度波引起的能隙的存在；在T=T^0，电子比热系数发生了从增大到减小的转折变化。

英文摘要：

The LUMO-HOMO energy gaps in YBa2Cu3O7 have been calculated with density functional theory on a cluster model of unit cell of 39 atoms in a wide range of temperatures （5-300 K）. Based on the energy gaps, the specific heat of electron and its coefficient have been calculated with bipolarons and thermally excited polarons model. The calculated results show that the superconducting critical temperature of YBa2Cu3O7 is 93 K. The energy gaps reach minimum which is not zero at Tc; the transition points at energy gap curve are corresponding respectively for Tc, T^＊ and T^0. The superconducting condensed matter disappear and exhibits diamagnetnism pairing pseudogap in a range of temperatures （93-120 K）. The energy gap is aroused by the charge density wave of the periodic stripes phase in a range of temperature （120-200 K）. When the temperature around T=T^0, the curve of the specific heat coefficient of electron changes from increased to decreased.