共查询到19条相似文献,搜索用时 127 毫秒
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根据近年发展起来的Mbius变换方法,从铁的结合能出发,反演计算出铁中原子间的相互 作用势.利用得到的相互作用势直接计算了原子力常数,并进而计算了铁的声子谱.计算中发 现,在研究铁中原子间相互作用时,仅考虑二体相互作用是不够的,还必须考虑三体相互作 用,采用Slater-Kirkwood型三体势,计算结果表明,在考虑三体势后,在三个主要对称方 向[100],[110],[111]上,计算结果与实验值得到了满意的符合.
关键词:
原子间相互作用势
声子谱
Mbius变换 相似文献
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本文在声子色散和库仑束缚势的影响下利用压缩态变分法计算了抛物量子点中弱耦合极化子的基态能量。采用的变分方法是基于逐次正则并且利用单模压缩态变换处理通常被我们所忽略的在第一次幺正变换中产生的声子产生湮灭算符的双线性项。计算得出了在考虑声子色散和库仑束缚势的情况下抛物量子点中弱耦合极化子的基态能量的数学表达式。讨论了在弱耦合情况下,受限长度,电子-声子耦合常数,色散系数,库仑结合参数与基态能量之间的依赖关系。 相似文献
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冀文慧 《原子与分子物理学报》2015,32(6)
利用线性组合算符和幺正变换相结合的方法,研究了声子色散对抛物量子点中弱耦合磁极化子电子周围光学声子平均数的影响.计及纵光学(LO)声子色散,在抛物近似下导出了基态能量与量子点有效受限长度、声子色散系数、回旋共振频率以及电子-声子耦合常数之间的关系,电子周围光学声子平均数与声子色散系数以及电子-声子耦合常数的关系.数值计算结果表明在弱耦合情况下抛物量子点中磁极化子的基态能量随声子色散系数的增大而减小;电子周围光学声子平均数随声子色散系数增大而增大,随电子-声子耦合常数的增大而增大. 相似文献
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利用线性组合算符和幺正变换相结合的方法,研究了声子色散对抛物量子点中弱耦合磁极化子电子周围光学声子平均数的影响。计及纵光学( LO)声子色散,在抛物近似下导出了基态能量与量子点有效受限长度、声子色散系数、回旋共振频率以及电子-声子耦合常数之间的关系,电子周围光学声子平均数与声子色散系数以及电子-声子耦合常数的关系。数值计算结果表明在弱耦合情况下抛物量子点中磁极化子的基态能量随声子色散系数的增大而减小;电子周围光学声子平均数随声子色散系数增大而增大,随电子-声子耦合常数的增大而增大。 相似文献
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Ping Liu Wenlan Xu Wei Lu 《International Journal of Infrared and Millimeter Waves》2001,22(3):469-476
The dispersion curves of PbTiO3 in both tetragonal (ferroelectric) and cubic (paraelectric) phases are calculated using the rigid-ion model with a small set of parameters. The soft modes in two phases are discussed. 相似文献
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Jinna Li Ming Luo Wenjian Weng Kui Cheng Piyi Du Ge Shen Gaorong Han 《Applied Surface Science》2009,256(1):342-345
Uniformly distributed PbTiO3 nanodots were successfully prepared by phase separation approach. A precursor sol film was first spin-coated on Si wafer and then spontaneously separated into two distinct phases owing to the Marangoni instability. PT nanodots with tailorable size and density were obtained after further heat treatment. X-ray diffraction analysis indicated that these nanodots showed a perovskite structure. An excellent room temperature field emission property of PbTiO3 nanodots was observed: the minimum turn-on voltage was about 5.3 V/μm; while the emission current density reached about 270 μA cm−2 at an applied field of about 9.25 V/μm. 相似文献
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First-principles study of structural stability and elastic property of pre-perovskite PbTiO3 下载免费PDF全文
The structural stability and the elastic properties of a novel structure of lead titanate, which is named pre-perovskite PbTiO3 (PP-PTO) and is constructed with TiO6 octahedral columns arranged in a one-dimensional manner, are investigated by using first-principles calculations. PP-PTO is energetically unstable compared with conventional perovskite phases, however it is mechanically stable. The equilibrium transition pressures for changing from pre-perovskite to cubic and tetragonal phases are -0.5 GPa and -1.4 GPa, respectively, with first-order characteristics. Further, the differences in elastic properties between pre-perovskite and conventional perovskite phases are discussed for the covalent bonding network, which shows a highly anisotropic character in PP-PTO. This study provides a crucial insight into the structural stabilities of PP-PTO and conventional perovskite. 相似文献
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Xuedong Li Hongli GuoHong Liu Dingquan XiaoJianguo Zhu 《Applied Surface Science》2011,257(15):6756-6760
0.95Pb(Sc0.5Ta0.5)O3-0.05PbTiO3 thin films were prepared on LaNiO3/SiO2/Si substrate by radio frequency magnetron sputtering, and the films were annealed subsequently with repeated many times by two approaches: normal one-step rapid thermal annealing and innovative two-steps rapid thermal annealing. X-ray diffraction demonstrates that all the films were preferred (1 0 0) oriented and an appropriate repeat of annealing process can enhance perovskite phase of the films. Scanning electron microscopy suggests that the films treated by two-steps rapid thermal annealing show crack-free, uniform size grains and dense microstructure. Measurement of remnant polarization and leakage current dependence of electric field confirms that the films treated by two-steps rapid thermal annealing exhibit better ferroelectric properties than the films treated by one-steps rapid thermal annealing. The results reveal that microstructure plays an important role in enhanced ferroelectric properties of the 0.95Pb(Sc0.5Ta0.5)O3-0.05PbTiO3 thin films. 相似文献
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讨论了利用分子场近似结合中子衍射或X射线衍射的实验结果计算R2Fe17型稀土过渡族化合物中稀土磁矩与过渡族磁矩之间交换耦合常量的方法,并据此计算了R2Fe17-xAlx(R=Tb,Dy,Ho,Er,Gd,x=7或8)化合物中稀土磁矩与过渡族磁矩之间的交换耦合常量.计算结果与实验值符合较好.
关键词:
2Fe17-xAlx化合物')" href="#">R2Fe17-xAlx化合物
交换耦合常量 相似文献
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研究了K3C60单晶薄膜在200K附近的导带结构.样品温度为190K时,同步辐射角分辨光电子谱能够观察到[111]方向有规律的能带色散.而在220K附近色散不存在.这一实验结果与K3C60在200K存在取向相变相符合.用反铁磁Ising模型对实验结果进行了分析.结果表明,K3C60在200K的相变是由低温下的一维无序取向结构转变为200K以上的双取向结构畴与无序分子(约占40
关键词:
3C60')" href="#">K3C60
取向相变机理 相似文献
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采用ab initio MP2/6-31+G方法计算了ArS2体系分析势能函数.并在此基础上, 对Ar+S2的非反应动力学过程进行了研究.结果表明,Ar与S2的结合 为很弱的物理吸附,其间没有化学键生成.在所计算的能量范围,Ar与S2的动力 学过程主要是非弹性碰撞.通过对非弹性碰撞产物的分析,结果显示Ar原子对S2 基态(X3Σ-g
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2')" href="#">ArS2
分析势能函数
反应动力学
碰撞激发 相似文献