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The all-electron full potential augmented plane-wave plus local orbital (APW_Io) method with the local-density approximation (LDA) is used to calculate the static equation of state (EOS) and elastic constants of crystalline GaSe. After the full relaxation of atomic positions, the calculated band structure at ambient pressure is consistent with the experimental data to the extent expected to give the known limits of LDA one-electron energies. The equilibrium lattice parameters found here exhibit the usual LDA-induced contraction. However, constrained with the experimental cell volume, the interlayer separation exhibits an expansion due to the LDA underestimate of the weak interlayer bonding. The calculated values of elastic constants are in good agreement with acoustic measurements. The pressure derivatives of the lattice constants derived from the theoretical elastic constants are in very good agreement with x-ray spectra measurements. Two analytical EOSs have been determined at pressures up to 4.5 GPa. The pressure evolution of the structure indicates that the layer thickness decreases slightly under pressure. 相似文献
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利用多道可见光谱探测系统测量了Hα、CⅢ(464.7nm)和OⅡ(441.5nnm)谱线的时间行为,得出了碳、氢和氧元素的入射通量。在简化模型下算出了氧碳间的化学溅射率,结果表明HT-6M托卡马克边界杂质产生机制主要是氢氧间的化学溅射和氧碳间的化学溅射,因此控制氧杂质尤其重要。 相似文献
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在密度泛函理论(DFT)广义梯度近似(GGA)下。用全势线性缀加平面波(FP—LAPW)方法计算了Ⅲ~Ⅳ族层状化合物CaSe晶体ε相的能带结构。计算得到的能隙宽度(1.015eV)以及布里渊区高对称点处的能量值,与最近的理论计算结果和实验数据符合得较好。 相似文献
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在密度泛函理论(DFT)广义梯度近似(GGA)下,用全势线性缀加平面波(FP-LAPW)方法计算了Ⅲ~Ⅳ族层状化合物GaSe晶体ε相的能带结构.计算得到的能隙宽度(1.015eV)以及布里渊区高对称点处的能量值,与最近的理论计算结果和实验数据符合得较好. 相似文献
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基于第一性原理的自洽场密度泛函理论(DFT)和广义梯度近似(GGA),利用缀加平面波加局域轨道(APW+lo)近似方法,建立了五层层晶超原胞模型,模拟了GaAs(110)表面结构和单个Xe原子在其表面的吸附.利用牛顿动力学方法,对GaAs(110)表面原子构形的弛豫和Xe原子在GaAs(110)表面的吸附进行了计算.从三种不同的初始构形出发,即Xe原子分别在Ga原子的顶位,As原子的顶位以及桥位,都发现Xe原子位于桥位时体系能量最低.由此,认为Xe原子在GaAs(110)表面的吸附位置在桥位,并且发现吸附Xe原子后GaAs(110)表面有趋向于理想表面的趋势,表面重构现象趋于消失,表面原子间键长有一定的恢复,这与理论预言相符合.
关键词:
密度泛函理论
表面结构
APW
表面原子吸附 相似文献
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Decoherence Effects of Terahertz Generation in Solids under Two-Color Femtosecond Laser Fields 下载免费PDF全文
We theoretically investigate terahertz emission from solid materials pumped by intense two-color femtosecond laser field in the presence of decoherence effects.Quantum-mechanical simulations are based on the length gauge semiconductor Bloch equations describing the optical excitation and decoherence with phenomenological dephasing and depopulation times.Contributions of interband and intraband mechanisms are identified in time domain,and the latter has dominated THz generation in solid-state sys... 相似文献
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