Thoretical Study on Electronic Structures and Pressure-Induced Composite Phase Transitions of Solid Oxygen

固氧电子结构与压力诱导复合相变的理论研究

• 批准号: 09640433
• 负责人: SUZUKI Naoshi
• 金额: $ 1.92万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640433/
• 关键词: solid oxygen; molecular phase; FP-LMTO method; electronic band structure; insulator-metal transition; band-overlapping; solid selenium; superconductivity; フルポテンシャルLMTO法; 反強磁性状態; 圧力誘起絶縁体-金属転移; 電荷分布とスピン分布; β-Po構造とbcc構造; 圧力誘起非金属-金属転移; 多軌道ハバードモデ

From band structure calculations using full-potential (FP)-LMTO method for molecular phases of oxygen we have obtained the following important results:1. At ambient pressure the most stable state is the AF state.2. Pressure-induced insulator-metal transition occurs by band overlapping which closes the indirect energy gap. At the transition volume VィイD2MィエD2=25.98 ÅィイD13ィエD1, the magnetic moment still remains in each molecule.3. With farther decreasing the volume the magnetic moment disappears and the paramagnetic metallic phase is realized at VィイD2MィエD2=11.36 ÅィイD13ィエD1 which corresponds to the ζ-phase at 116 GPa.In order to see a possibility that the observed metallization is realized in a monatomic phase of solid oxygen we have performed band calculations of monatomic phases for the volume corresponding to that of the ζ-phase at 116 GPa(VィイD2MィエD2=11.36 ÅィイD13ィエD1). As the crystal structure we have chosen the β-Po type because it is the monatomic structure realized first under high p … More ressures in other VI-b elements. The β-Po type structure is rhombohedral and the sc, bcc and fcc structures are realized for special values of c/a of β-Po type structure. We have found that the total energy of β-Po oxygen is higher than that of the molecular ζ(monoclinic) phase obtained for the same volume. Therefore, judging from all the results of our calculations it is strongly suggested that a paramagnetic metallic state is realized in molecular solid oxygen under high pressures higher than about 100 GPa.We investigated also pressure-induced superconductivity of β-Po Se (60 Gpa < P < 150 Gpa) and of bcc Se (150 Gpa < P) in the frame work of Allen-Dynes formalism. In the bcc phase the superconducting transition temperature TィイD2cィエD2 increases considerably with decreasing pressure, and TィイD2cィエD2 reaches more than 10 K at the transition from bcc to β-Po. The origin of this remarkable increase of TィイD2cィエD2 is mainly attributed to phonon anomaly in the middle of the ГN line. In β-Po phase, on the other hand, TィイD2cィエD2 is almost pressure independent (〜5K) and there is a large jump in TィイD2cィエD2 at the transition from β-Po to bcc. Less

用全势（FP）-LMTO方法计算了氧分子相的能带结构，得到了以下重要结果：1。在环境压力下，最稳定的状态是AF状态。压力诱导的绝缘体-金属转变通过带重叠发生，从而关闭间接能隙。在过渡体积V D2 M D2=25.98 D13 D1处，磁矩仍然保留在每个分子中。随着体积的进一步减小，磁矩消失，顺磁金属相在V_（10）D_2 M_（10）D_2 =11.36 V_（10）D_（13）D_1处实现，这对应于116 GPa下的γ相。116 GPa下的相位（V_（10）D_2 M_（10）D_2 =11.36 V_（10）D_（13）D_1）。作为晶体结构，我们选择β-Po型，因为它是在高p下首先实现的单原子结构 ...更多信息 其他VI-B元素的压力。β-Po型结构为菱面体结构，当β-Po型结构的c/a为特定值时，可实现sc、bcc和fcc结构。我们发现β-Po氧的总能量高于相同体积下得到的分子单斜相的总能量。因此，从我们的计算结果来看，在高压下（大于100 GPa），分子固体氧中实现了顺磁金属态.我们还在Allen-Dynes理论框架下研究了β-Po Se（60 GPa < P < 150 GPa）和bcc Se（150 GPa < P）的压致超导性.在体心立方相，超导转变温度T_（2c）T T_（10）D_（20）C_（20）D_（2而在β-Po相中，T_（10）D_2c_（10）D_2几乎与压力无关（0.5K），在β-Po相转变为bcc相时，T_（10）D_2c_（10）D_2有一个很大的跃变。少

项目成果

M. Otani: "Theoretical Study on Magnetic Properties of Low-Dimensional Oxygen Molecular Assemblies"Physica B. 265. 60-64 (1999)

M. Otani：《低维氧分子组装体磁性的理论研究》Physica B. 265. 60-64 (1999)

H. Miyagi: "First-Principles Study of Iodine and Bromine under High Pressure"J. Phys. Condens. Matter. 10. 11203-11213 (1998)

H. Miyagi：“高压下碘和溴的第一性原理研究”J。

M. Otani: "Pressure-Induced Insulator-Metal Transition of Solid Oxygen - Band Structure Calculations" J. Phys.: Condens. Matter. 10. 11603-11606 (1998)

M. Otani：“固体氧的压力诱导绝缘体-金属转变 - 能带结构计算”J. Phys.：Condens。

M. Otani: "First-Principles Calculations of Electronic Band Structures of High Pressure Phases of Solid Oxygen" Rev. High Press. Sci. Tech.7. 178-180 (1998)

M. Otani：“固体氧高压相电子能带结构的第一原理计算”Rev. High Press。

M.Otani: "Theoretical Study on Electronic Structure and Lattice Dynamics of Solid O and Se under High Pressures"Rev. High Press. Sci. Tech.. (in press).

M.Otani：“高压下固体O和Se的电子结构和晶格动力学的理论研究”Rev。