极端条件下^6Li2O的热力学性能与电子结构

Thermodynamic properties and electronic structuresof ^6Li2O under extreme condition

采用密度泛函理论与准谐振德拜模型研究了面心立方相的6Li2O在极端条件下的热力学性质与电子结构。结果表明:6Li2O的热膨胀系数在任何温度下都随压强增加明显降低,但仅当压强较低(低于40GPa)时,温度对6Li2O的热膨胀系数的影响才明显;O原子半径随压强增大而迅速降低,而随温度的变化并不明显;在低压条件下(低于40 GPa),带隙随温度的升高缓慢降低;而在高压条件下(高于40 GPa),温度对带隙宽度的影响几乎可以忽略;无论在什么温度条件下,带隙宽度均随压强的增大而迅速增加。

Thermodynamic properties and electronic structure of surface heart cubic phase fcc-6Li2O is studied by DFT and quasi-harmonic Debye model.Thermal expansion coefficient of 6Li2O reduces obviously with increased pressure under any temperature.Under low pressure（less than 40 GPa）,temperature can cause distinct variety of thermal expansion.Radius of O atom decreases rapidly with pressure,but change caused by temperature is obscure.Under lower pressure（less than 40 GPa）,band gap reduces just a little with temperature.Whereas,changes caused by temperature will almost be ignored under high pressure（more than 40 GPa）.With raising of pressure,transition of electrons in valence band to high level will produce increasing of band gap.