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1.
几种碳团簇的几何构型及电子结构的计算   总被引:2,自引:0,他引:2  
对电子结构计算中常用的量子化学从头算方法及几种量子化学半经验计算方法进行了讨论,采用这几种电子结构计算方法对C4、C8、C20和C60团簇的几何构型进行了优化,并对几种计算结果进行了比较.对于碳团簇MINDO/3、MNDO、MNDO/d、AM1及PM3五种半经验方法与从头算方法计算结果接近,而且极大地缩短了计算时间。  相似文献   

2.
本文阐述了量子化学的从头(ab initio)计算方法和半经验(semiempirical)方法,以及目前国际上流行的各种量子化学的主要计算方法.  相似文献   

3.
该文用三种参数化的量子化学方法和从头计算(采用4-31G基组)研究了四唑两种异本间异构反应,给出了反应的活化能和内禀反应坐标(IRC)途径。  相似文献   

4.
聚苯硫醚交联反应机理的量子化学计算研究   总被引:3,自引:0,他引:3       下载免费PDF全文
用量子化学从头计算方法,利用静态理论对聚苯硫醚(PPS)的交联机理进行了研究,通过对PPS分子模型和可能产生的自由基模型的量子化学计算,探讨了PPS的热交联反应趋势和交联结构,证实了氧在交联中所起的重要作用。  相似文献   

5.
运用G94程序,采用HF方法LANL2DZ基组对于还原型FeSOD的晶体结构活性中心进行了量子化学从头计算,获得了分子轨道能量,电荷分布及原子轨道对前沿分子轨道贡献的信息。结果表明,其活性中心易于接受超氧自由基(O2^-.)的进攻并完成其生理功能。  相似文献   

6.
量子化学研究方法及其在结构化学中的应用   总被引:1,自引:0,他引:1  
本概括地介绍了量子化学的研究方法,讨论了各种量子化学计算方法的发展现状及其在结构化学中的应用,指出Xa方法和从头计算法是计算含重元素化合物的最有效方法。  相似文献   

7.
对含有动力学抑制剂的水合物体系中的氢键,应用量量子化学MP2从头计算方法在6-31G(d)的基组水平上进行几何优化,计算了水分子之间和抑制剂与水分子之间形成的氢键键长、电子密度和相互作用能,从量子化学角度探讨了水合物动力学抑制剂的作用机理.计算结果表明动力学抑制剂与水分子形成的氢键明显强于水分子之间形成的氢键,抑制剂通过与水分子形成氢键阻止了水合物进一步生成.  相似文献   

8.
钇原子簇的量子化学从头计算廖代伟(化学系物理化学研究所)与镧系、锕元素同在ⅢA族的钇具有(Kr)4d ̄15S ̄2的电子构型。与大多数具有磁性的稀土族元素的离子不同。Y ̄(3+)因没有不成对的电子而具有反磁性.Y_2O_3是一种固体碱催化剂,可催化丁烯...  相似文献   

9.
用从头计算研究煤表面与甲烷分子相互作用   总被引:14,自引:0,他引:14  
依据所提出的煤表面原子簇模型,量子化学从头计算(STO-4-31G)表明甲烷分子与煤表面相互作用是各向异性的,最大作用势(吸附势)为2.65KJ/mol,旋转势垒为1.34KJ/mol。结果表明甲烷在煤粒表面上的吸附属物理过程(表面凝聚)。  相似文献   

10.
采用量子化学中的从头计算(abinitio)方法,在HF/3-21G和HF/6-31G*水平上分别计算研究了亚甲二醇二硝酸酯(MGDN)的旋转构象和电子结构,计算所得MGDN绕C—O键旋转的能垒较低(约6kJ/mol),其平面构象的能量最高.能量最低的构象(亦即最稳定构型或平衡几何构型)的2个酯基均绕C—O键旋转77.4°.不同构型的电荷分布差异较小.  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.
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   

13.
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   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

16.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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