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基于密度泛函理论的第一性原理方法, 系统地研究了Li-N-H储氢过程中各个化合物的晶胞参数、生成焓和化学反应焓. 结果发现优化后的晶格参数与先前的理论和实验研究符合得很好. 通过计算Li3N, LiH, LiNH2和Li2NH在298 K的生成焓分别为-168.7, -81.0, -173.0和-190.8 kJ/mol, 进而计算得到整个储氢反应过程在T=298 K时反应焓为78.5 kJ/mol H2, 这和他人计算得到T=300 K的结果75.67 kJ/mol H2非常接近. 最后, 给出了储氢两步反应过程分别在T=298 K时的反应焓, 这些结果都与实验和他人理论计算得到的数据符合较好.
关键词:
第一性原理
热力学性质
Li-N-H 体系
反应焓 相似文献
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应用Gaussian 98程序对U-H2O体系所有可能的构型进行优化计算-采用密度泛函 理论的B3L YP方法和MP2方法,对铀原子采用相对论有效原子实势及(6s5p2d4f)/[3s3p2d2f]收缩价基 集合,氧、氢原子采用6-311G**全电子基集合-计算得到了6种五重态的相对稳 定结构 的电子状态、几何结构、能量、谐振频率、力学性质和电性质等-结果表明,H2 O蒸汽在金 属铀表面的反应首先是铀和氧的相互作用-对C2v关键词:
密度泛函理论
B3LYP
分子结构
热力学函数 相似文献
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热力学的拉格朗日函数 总被引:2,自引:0,他引:2
Planck和Pauli提出了相对论热力学Lageange函数的一促形式,本文表明:在不同的约束条件下,Lagrange函数的形式是不同的,它可以分别是内能、焓、Helmholtz自由能、Gibbs函数、巨势等和负值;文中对该函数的相对论变换性质也进行了讨论。 相似文献
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认为黑洞的熵正比于视界面积的熵公式S=A/4不能满足热力学第三定律,提出了新的熵公式,它既能满足热力学第三定律,又能推出黑洞的温度的表达式.
关键词:
黑洞
熵
热力学第三定律 相似文献
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以洛伦兹变换为基础讨论了理想气体体积、 压强、 内能、 温度、 熵等热力学量的相对论变换, 并从理想
气体状态方程和理想气体摩尔热容的角度说明了普朗克、 爱因斯坦和德布罗意给出的相对论温度变换更加合理 相似文献
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利用负温度高能离子束的相对论多普勒效应,可能实现从红外到X射线连续调谐激光器。调谐范围△νT=2ν0βγ。离子束从零到c调速时,激光频率为0—∞。本文给出了激光参数的相对论变换式,计算了负温度相对论离子束激光器的增益、阈值和输出特性,提出了用激光束对相对论离子束进行共振激发的方法,并讨论了He+离子束及Ar+离子束激光器的设计参数。
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Some problems in relativistic thermodynamics 总被引:1,自引:0,他引:1
É. V. Veitsman 《Journal of Experimental and Theoretical Physics》2007,105(5):1057-1067
The relativistic equations of state for ideal and real gases, as well as for various interface regions, have been derived. These dependences help to eliminate some controversies in the relativistic thermodynamics based on the special theory of relativity. It is shown, in particular, that the temperature of system whose velocity tends to the velocity of light in vacuum varies in accordance with the Ott law T = T 0/√1 ? v 2/c 2. Relativistic dependences for heat and mass transfer, for Ohm’s law, and for a viscous flow of a liquid have also been derived. 相似文献
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Martin Schwarz Jr. 《Journal of statistical physics》1976,15(3):255-261
In the present study we investigate the statistical thermodynamics of the anharmonic oscillator, whose energies are characterized by the potential 1/2x
2+x
4. Employing the energies recently obtained by Hioe and Montroll, we compute the partition function and the thermodynamic quantities for the anharmonic and quartic oscillators. Low- and high-temperature formulas are presented for the thermodynamic quantities of the oscillators. 相似文献
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应用实空间重正群方法于一维具L-近邻键的点-渗流及键-渗流模型,得到类-温度标度率与类-场标度率,再利用普适标度律得到全部临界指数的精确结果。对于点-渗流模型有αp=2-L,βp=0,γp=L,δp=∞,ηp=1及vp=L。这与生成函数方法结果一致;对于键-渗流模型有αp=2-(L(L+1))/2,βp=0,γp=(L(L+1))/2,δp=∞,ηp=1及vp=(L(L+1))/2,其中的“热”临界指数与转移矩阵方法结果一致,磁临界指数是新的结果。由点-渗流及键-渗流模型求出Suzuki的弱普适律的重正化临界指数为φ≡(2-α)/v=1,β≡β/v=0,γ≡γ/v=1,δ≡δ=∞及η≡η=1。即重正化的临界指数不仅与L无关,而且也不依赖于是点抑键的渗流模型,即普适律对Suzuki重正化临界指数仍得以保持。
关键词: 相似文献
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固态相变中相界面或畴界面的平均运动速度V与有效相变驱动力△G'(相变驱动力△G与相界面运动阻力△GR之差)之间的关系可表示为V=φ(△G—△GR)。当有单向变化的外场(场强为ξ,变化速率为ξ)作用于相变系统并能诱导相界面运动时,就会产生母相/新相间的转变。在相变过程中同时叠加一个交变应力时,则可计算得界面动力学关系V=φ(△G—△GR)与相变过程内耗Q-1、相关的模量亏损(△M/M)、相变速率dF/dξ、相变应变ε0间的关系为 [d lnφ(△G-△GR)/d(△G-△GR)]= Q-1ω/n2M(dF/dξ)ξ = (△M/M)ω/nMε0(dF/dξ)ξ, 以及 (△M/M)/Q-1=ε0/n。此处ω为交变应力的圆频率,M为与振动模式有关的弹性模量,n为应力与界面运动的耦合因子。因此,界面动力学关系式的通解为 V = ∑(±n)/(α≠-1) Aα exp{[(△G-△GR)/△Gα*]α+ 1/(α+ 1)} +∑(m)/(β0) Aβ[(△G-△GR)/△Gβ*]β 此处n,m为正整数。上式中的各项参数可由实验数据确定。此外,(△M/M)/Q-1的等式还可用于判别相变过程的模量亏损中有无声子模软化的贡献。
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The heats of formation of haloacetylenes are evaluated using the recent W1 and W2 ab initio computational thermochemistry methods. These calculations involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh quality, extrapolations to the one-particle basis set limit, and contributions of inner-shell correlation, scalar relativistic effects. and (where relevant) first-order spin-orbit coupling. The heats of formation determined using W2 theory are: δH1 298(HCCH) = 54.48 kcal mol?1, δHf 298(HCCH) = 25.15 kcal mol, δHf 298(FCCF) = 1.38 kcal mol?1, δHf 298(HCCC1) = 54.83 kcal mol?1, δHf 298(CICCC1) = 56.21 kcal mol?1, and δHf 298(FCCC1) = 28.47 kcal mo1?1. Enthalpies of hydrogenation and destabilization energies relative to acetylene were obtained at the WI level of theory. So doing we find the following destabilization order for acetylenes: FCCF > ClCCF > HCCF > ClCCCl > HCCCI > HCCH. By a combination of WI theory and isodesmic reactions. we show that the generally accepted heat of formation of 1,2-dichloroethane should be revised to ?31.8 ± 0.6 kcal mol?1, in excellent agreement with a very recent critically evaluated review. The performance of compound thermochemistry schemes, such as G2, G3, G3X and CBS-QB3 theories, has been analysed. 相似文献
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What are the differences between Hantzsch ester and H2 as two‐hydrogen‐atom donors in acetonitrile on the thermodynamics of elementary steps?
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Thermodynamic driving forces of eight possible elementary steps for Hantzsch ester and six possible elementary steps for H2 to release two hydrogen atoms (2H?) or ions (H? and H+) in acetonitrile were examined using experimental method or the available related thermodynamic data for the first time, which can facilitate chemists to choose a suitable reducing agent between Hantzsch ester and H2 to reduce a given organic unsaturated compound in acetonitrile and make a rational diagnosis on the detailed reaction mechanisms. The focus of this paper is to compare the differences between Hantzsch ester and H2 to release two hydrogen atoms (or ions) on the thermodynamics of elementary steps in acetonitrile. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Hadron thermodynamics deals with a gas of indistinguishable particles whose mass spectrum is taken to have the formKm
a
e
bm
. A long-standing inconsistency is pointed out, namely the nonextensive nature of the entropy found in some treatments by way of the microcanonical ensemble, which contrasts with the extensive nature found by way of the canonical ensemble. The former result is due to an error. After correction, the two ensembles are found to lead to the same expressions for the thermodynamic quantities ifa –7/2. Some of these expressions are new. Fora<–5/2, the microcanonical approach is used to examine a model in which one particle is appreciably heavier than the rest. However, the resulting entropy is found to be unphysical. 相似文献