首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
用MS-Xα方法研究了Fe8原子簇(具有D6h对称)和Fe15原子簇(具有Oh对称)的电子结构,结果表明:⑴两种原子簇中的Fe原子磁矩及其d能带中的交换劈裂性质互不相同;⑵两类原子簇中的电荷分布不是均匀的,电荷倾向于从外围原子向内部原子上转移,并且被转移电子的自旋方向(正自旋或负自旋)与原子簇的对称性质密切相关。  相似文献   

2.
利用DFT(密度泛函理论)方法对系列原子簇NixFe(x=1—5)进行优化计算,通过分析各种不同比例组成的原子簇NixFe(x=1—5)的能量、结合能及Fe磁矩,结果发现不同Ni、Fe比例的各原子簇均能稳定存在,尤以原子簇Ni,Fe的结合能最大,最为稳定;随着原子簇中Ni含量的增加,Fe原子3d轨道电子产生的磁矩呈现先减少再增加的趋势。  相似文献   

3.
本文利用离散变分—局域自旋密度泛函 ( DV- LSD)的方法对 Pd N原子簇的电子结构和磁性性质进行了研究。结果表明 :所有我们研究的钯原子簇都存在非零磁性解 ,原子的平均磁矩随着原子簇的尺寸增大而逐步减小  相似文献   

4.
采用离散变分法从电子结构和磁性的角度对Ag13进行研究.计算发现Ag13具有Ih对称性的几何结构和畸变的Oh结构,它们都是稳定的几何结构,而且结合能相差极小.但是Ih结构对应5个μB的磁矩,而畸变的Oh结构只有一个μB的磁矩.它们磁性的差异完全是由几何效应引起的.  相似文献   

5.
本课件以Authorware和3D-Max为制作平台,引导学生进行探究式学习,进行了原子簇多酸配合物的多面体结构、球棍结构以及文本制作等内容的三维多媒体动画制作.通过三维动画,生动直观地展现出了原子簇典型化合物的结构、键和以及配位几何构型,使原子簇化学基础知识的教与学达到了前所未有的教学效果.  相似文献   

6.
利用密度泛函理论(DFT)方法,在B3LYP/Lan12dz水平下,对原子簇CoMn2B2的14种可能构型分别在二、四重态下进行全参数优化计算和频率验证,获得了6种二重态稳定构型,6种四重态稳定构型;分别对这些稳定构型的能量、电荷分布、不同构型磁矩的情况进行研究分析。结果表明:原子簇CoMn2B2所有构型中1(4)最稳定。原子簇CoMn2B2中各原子所带电荷受多重态的影响较小,Mn原子带负电,Co原子和B原子带正电。Mn原子的外层轨道布居数变化较大。Mn原子和Co原子的磁矩主要受原子簇的多重度的影响较大。  相似文献   

7.
利用Gussian-98程序,B3LYP方法,在6-311G^*水平上对Si4X(X=C^*,N,O,F,Si,P,S,Cl)原子簇的几何构型进行优化和频率计算。得出各原子簇的稳定结构。结果表明,Si5原子簇的最稳定构型具有D3b对称性,用杂原子X(X=C,N,O,F,P,S,Cl)取代Si5原子簇中的Si原子,几乎都得到C3v和C2y对称的稳定构型(Si4F原子簇只有C2v对称的稳定构型,Si4Cl原子簇不存在这两种稳定构型)。对具有相同对称性的杂原子簇中Si—X键长变化规律进行研究。发现同一周期从左到右,Si—x键长与其对应的原子共价半径和相比较,其键长变化率逐渐增大,杂原子的加入对原Si5原子簇中的其它Si-Si键长影响不大。  相似文献   

8.
利用离散变分-局域自旋密度泛函方法对Rh13原子簇在进行了电子组态优化和键长优化的基础上,计算得到了原子簇的平衡键长、结合能、态密度分布和净磁矩,所得与实验更为接近,对理论计算值与实验结果的差异给出了可能的解释。  相似文献   

9.
采用密度泛函方法B3LYP/6311SDD方法系统研究了掺钌硅原子簇RuSin (n = 1-14) 的几何结构、稳定性以及电子性质。研究结果表明,当n 3时,RuSin的基态结构由平面结构转为三维的立体结构。随着硅原子数由1增长到14,RuSin原子簇中Ru原子的位置逐渐从原子簇表面转移到原子簇内部。当n = 12时,Ru原子完全陷入了原子簇结构中,形成一个以钌为中心的硅笼结构。自然键轨道分析表明RuSin(n = 2-14)的基态结构中都存在三中心键,证明了这些结构的稳定性。此外,RuSin (n = 1-14)原子簇各基态结构的平均结合能、二阶差分能、HOMO-LUMO能隙、电离势、电子亲和势等信息表明RuSi12的基态结构有着很高的稳定性。  相似文献   

10.
利用DFT在B3LYP/Lan12dz水平下对原子簇Fe4BP的所有可能构型进行全参数优化,经过频率验证,获得8种稳定构型,分析各构型的几何参数、成键及电子转移情况,发现Fe-B和Fe-P键是原子簇稳定性的主要贡献者;原子簇Fe4BP存在Fe-P的择优键合;原子簇电荷转移是从类金属到金属。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

19.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

20.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号