共查询到20条相似文献,搜索用时 15 毫秒
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采用微正则系综理论和嵌入原子模型计算了原子数为16-152之间7个Aun团簇碰撞合并过程。结果表明:碰撞能量大于0.3eV时,团簇处于熔融态,碰撞能量是合并过程的主导因素,碰撞能量小于0.3eV时,团簇处于凝固态,碰撞能量和结合能共同影响合并过程;碰撞能量小于0.1eV时,在结合能作用下,团簇结构随碰撞能量增加发生变化,其中壳层结构势能较低,稳定性较好。 相似文献
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U-Pu和U-Am混合氧化物中的Pu或Am含量对核反应堆燃料的高效循环利用至关重要.研究铀基混合氧化物中不同Pu或Am的含量对其结构、力学性质和能量的影响有助于理解和预测提高反应堆中燃料的行为以及与包层的化学或力学相互作用.本文通过DFT+U方法首先探索UO2、PuO2和AmO2的结构和能量随U的变化关系,然后研究UO2结构中不同Pu或Am含量对其结构和力学性质以及能量的影响.结果表明在UO2结构中掺入不同Pu或Am的含量均使得体系晶格参数收缩,且与实验观测(U, Pu)O2中Pu的含量结论是一致的.从能量角度观察,UO2结构中掺入不同Pu或Am的含量使得体系形成能随掺入量的变化趋势明显不同.结果显示当UO2结构中掺入Pu为25%时,U-Pu混合氧化物体系的形成能最低,而当UO2结构中掺入Am为75%时,U-Am混合氧化物体系的形成能最低.此外,我们也探讨和分析了在UO2 相似文献
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A mass–spring–damper system is at the core of both a vibration absorber and a harvester of energy from ambient vibrations. If such a device is attached to a structure that has a high impedance, then it will have very little effect on the vibrations of the structure, but it can be used to convert mechanical vibrations into electrical energy (act as an energy harvester). However, if the same device is attached to a structure that has a relatively low impedance, then the device may attenuate the vibrations as it may act as both a vibration absorber and an energy harvester simultaneously. In this paper such a device is discussed. Two situations are considered; the first is when the structure is excited with broadband random excitation and the second is when the structure is excited by a single frequency. The optimum parameters of the device for both energy harvesting and vibration attenuation are discussed for these two cases. For random excitation it is found that if the device is optimized for vibration suppression, then this is also adequate for maximizing the energy absorbed (harvested), and thus a single device can effectively suppress vibration and harvest energy at the same time. For single frequency excitation this is found not to be the case. To maximize the energy harvested, the natural frequency of the system (host structure and absorber) has to coincide with the forcing frequency, but to minimize vibration of the host structure, the natural frequency of the absorber has to coincide with the forcing frequency. In this case, therefore, a single resonator cannot effectively suppress vibration and harvest energy at the same time. 相似文献
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本文基于密度泛函理论(DFT)的第一性原理计算了W、Mn、V、Ti替位掺杂二维MoSi2N4后的几何结构、电子结构以及光学性质的变化.电子结构分析表明W、Mn、W、Ti替位掺杂二维MoSi2N4后的禁带宽度分别为1.806 e V、1.003 e V、1.218 e V和1.373 e V;四种过渡金属掺杂后MoSi2N4的带隙类型没有发生改变,均为间接带隙半导体;W掺杂后的杂质能级靠近价带顶,费米能级靠近价带顶,为p型半导体,杂质能级为受主能级;Mn掺杂后的杂质能级靠近导带底,费米能级靠近导带底,为n型半导体;V和Ti掺杂后杂质能级位于费米能级附近,为复合中心;光学性质分析表明,在2 e V~4 e V的能量区间内,W掺杂结构的吸收波长为336 nm,体系发生红移;Mn、V和Ti替位掺杂后的吸收波长分别为320 nm、358 nm和338 nm,且掺杂体系均发生蓝移. 相似文献
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The formation mechanism for the icosahedral central structure of the He1 13 cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between two nuclei at the center and an apex of the icosahedral central structure. The result of the calculation has shown that the curve has a minimal energy -37.5765 (a.u.) at R = 2.70ao. The binding energy of He 13 with respect to He 12He was calculated to be 1.4046 a.u. This means that the cluster of He 13 may be formed in an icosahedral central structure with strong binding energy. 相似文献
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本文提出了Li9团簇体心立方结构的形成机理,并对此结构的总能量随中心原子到顶点原子间核间距R的变化用芶氏改进的排列通道量子力学方法(MACQM)进行了计算。结果显示曲线在R = 4.77 a0处有一极小值 -67.160922 a.u.,这表明Li9团簇的体心立方结构是可能稳定存在的。在R趋于无穷大时这9个锂原子的总能量为 -66.852240 a.u.,所以形成Li9的总结合能为0.308682 a.u.。因此Li9 团簇的原子平均结合能是0.034298 a.u.或0.933 eV,它大于我们过去计算的Li5团簇正四面体中心结构的原子平均结合能0.632 eV、Li7 团簇正八面体中心结构的原子平均结合能0.674 eV和Li13 团簇正二十面体中心结构的原子平均结合能0.810 eV。故在体心正多面体结构Lin (n= 5 ,7,9,13)中,Li9的体心立方结构有最大的原子平均结合能,这也许是碱金属晶体的晶胞取体心立方结构的一个原因。 相似文献
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运用密度泛函理论体系下的平面波赝势(PWP)和广义梯度近似(GGA)方法,利用第一性原理计算了不同压强下六方纤锌矿结构AlN晶体的晶格常数、总能量、电子态密度、能带结构、光反射系数与吸收系数。通过比较能带结构的变化行为,得出 AlN在16.7Gpa附近存在等结构相变,即由直接带隙结构转变为间接带隙结构。同时,结合高压下的态密度分布图和能级移动情况,分析了AlN在高压下的光学性质,吸收谱有向高能端移动(蓝移) 的趋势。 相似文献
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运用密度泛函理论体系下的平面波赝势(PWP)和广义梯度近似(GGA)方法,利用第一性原理计算了不同压强下六方纤锌矿结构AlN晶体的晶格常数、总能量、电子态密度、能带结构、光反射系数与吸收系数。通过比较能带结构的变化行为,得出 AlN在16.7Gpa附近存在等结构相变,即由直接带隙结构转变为间接带隙结构。同时,结合高压下的态密度分布图和能级移动情况,分析了AlN在高压下的光学性质,吸收谱有向高能端移动(蓝移) 的趋势。 相似文献
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A systematic investigation is presented of the variation of isochromat structures with threshold voltage (quantum energies). With a double focusing X-ray monochromator highly resolved bremsstrahlung isochromats of tungsten are measured in the quantum energy range from 0.15 to 6 keV. Crystals with lattice constants up to about 50 Å could be used as dispersing devices. The initial parts of the isochromats (primary structure) turned out to be essentially independent of quantum energy. With the high resolution of the monochromator at quantum energies below 0.9 keV a fine structure in the primary structure of the corresponding isochromats could be observed. This fine structure is in qualitative agreement with a theoretical density of states calculated by Mattheiss. The following parts of the isochromats (secondary structure) depend strongly on quantum energy. These structures can be understood by the influence of characteristic energy losses in the target of the primary electrons. 相似文献
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First-Principles Investigation on the Fully Compensated Ferrimagnetic Behavior in Ti_2NbSb and TiZrNbSb 下载免费PDF全文
The electronic structures of Ti_2NbSb with Hg_2CuTi structure and TiZrNbSb with LiMgPdSn structure are investigated using first-principles calculations.The results indicate that Ti_2NbSb is a fully compensated ferrimagnetic spin-gapless semiconductor with an energy gap of 0.13 e V,and TiZrNbSb is a half-metallic fully compensated ferrimagnet with a half-metallic gap of 0.17 e V.For Ti_2NbSb,the total energy of the Hg_2CuTi structure is0.62 e V/f.u.higher than that of the L2_(1) structure,which is the ground state,and for TiZrNbSb,the total energy of the structure considered in this work is only 0.15 e V/f.u.larger than that of the ground state.Thus both of them may be good candidates for spintronic applications. 相似文献
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V. E. Shebalin A. V. Anisenkov V. M. Aulchenko N. S. Bashtovoy D. A. Epifanov L. B. Epshteyn A. A. Grebenuk F. V. Ignatov A. L. Erofeev O. A. Kovalenko A. N. Kozyrev A. S. Kuzmin I. B. Logashenko K. Yu. Mikhailov G. P. Razuvaev A. A. Ruban B. A. Shwartz A. A. Talyshev V. M. Titov Yu. V. Yudin 《Physics of Atomic Nuclei》2015,78(13):1544-1551
The structure of the barrel calorimeter of the CMD-3 detector is presented in this work. The procedure of energy calibration of the calorimeter and the method of photon energy restoration are described. The distinctive feature of this barrel calorimeter is its combined structure; it is composed of two coaxial subsystems: a liquid xenon calorimeter and a crystalline CsI calorimeter. The calorimeter spatial resolution of the photon conversion point is about 2 mm, which corresponds to an angular resolution of ~6 mrad. The energy resolution of the calorimeter is about 8% for photons with energy of 200 MeV and 4% for photons with energy of 1 GeV. 相似文献
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利用有限元模拟方法研究了内凹负泊松比蜂窝结构的面内双轴冲击响应。用节点扰动方法建立了具有不同规则度的内凹负泊松比蜂窝结构,并将其在不同冲击速度下的变形模态、应力-应变曲线和能量耗散能力与规则蜂窝进行了对比分析。结果表明,冲击速度是内凹蜂窝结构变形模态最主要的影响因素。此外,在双轴冲击下,由于不规则度的引入,延长了应力-应变曲线的平台阶段,抑制了结构的各向异性程度,从而使结构的变形特征从局部密实转向整体密实。在能量吸收能力方面,结构的不规则性导致了密实化阶段的滞后,因此在相同的压缩程度下,其塑性耗散能低于规则模型。 相似文献
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本文报道用两台连续激光级联共振的方法,测量了(255)~U的→16900→33625cm~(-1)跃迁的超精细光谱结构,给出了33625cm~(-1)能级的超精细结构常数A、B,从而给出一种测量难熔、有毒金属高激发态能级结构的简单且精确的方法. 相似文献
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Formation Mechanism and Binding Energy for Icosahedral Central Structure of He13^+ Cluster 总被引:5,自引:0,他引:5
ZHANGJian-Ping GOUQing-Quan LIPing 《理论物理通讯》2004,42(5):763-767
The formation mechanism for the icosahedral central structure of the He13^ cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between two nuclei at the center and an apex of the icosahedral central structure. The result of the calculation has shown that the curve has a minimal energy -37.5765 (a.u.) at R=2.70ao. The binding energy of He13^ with respect to He^ 12He was calculated to be 1.4046 a.u. This means that the cluster of He13^ may be formed in an icosahedral central structure with strong binding energy. 相似文献
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The paper presents the calculation of the energy of elastic stresses in the domain structure of uniaxial massive ferromagnetics. The inclusion of this energy permits the formation of a structure with walls perpendicular to the external field to be elucidated and the critical thickness of the sample on which this structure is realized to be determined. 相似文献
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A finite temperature theory is given of the temperature variation of the sound velocity and of the structure factor of liquid helium. The sound velocity is found to decrease slightly as the temperature is increased from absolute zero. The first peak of the structure factor is higher for higher temperature below the λ point. The internal energy is characterized by the quasiparticle distribution function with the Bogoliubov-Zubarev type excitation energy. The structure factor and the energy are determined by the effective interaction which depends on the average density, the density of the excited particles, and temperature in addition to the interaction potential. 相似文献