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Hydrogen storage in BC_3 composite single-walled nanotube:a combined density functional theory and Monte Carlo investigation 被引量:1
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作者 刘秀英 王朝阳 +2 位作者 唐永建 孙卫国 吴卫东 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第3期394-401,共8页
This paper applies a density functional theory (DFT) and grand canonical Monte Carlo simulations (GCMC) to investigate the physisorptions of molecular hydrogen in single-walled BC3 nanotubes and carbon nanotubes. ... This paper applies a density functional theory (DFT) and grand canonical Monte Carlo simulations (GCMC) to investigate the physisorptions of molecular hydrogen in single-walled BC3 nanotubes and carbon nanotubes. The DFT calculations may provide useful information about the nature of hydrogen adsorption and physisorption energies in selected adsorption sites of these two nanotubes. Furthermore, the GCMC simulations can reproduce their storage capacity by calculating the weight percentage of the adsorbed molecular hydrogen under different conditions. The present results have shown that with both computational methods, the hydrogen storage capacity of BC3 nanotubes is superior to that of carbon nanotubes. The reasons causing different behaviour of hydrogen storage in these two nanotubes are explained by using their contour plots of electron density and charge-density difference. 展开更多
关键词 bC3 composite nanotube hydrogen storage density functional theory (dft grandcanonical Monte Carlo method (GCMC)
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SO_(2)对K2CO_(3)吸附CO_(2)性能影响的实验及DFT机理研究 被引量:1
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作者 郭百合 李艳红 +3 位作者 张靖超 王彦霖 乔晓磊 金燕 《中国电机工程学报》 EI CSCD 北大核心 2024年第2期659-669,I0019,共12页
电站锅炉的尾气在脱硫后含有微量的SO_(2),导致CO_(2)吸附剂性能变差。根据电厂烟气的组分,采用模拟烟气在实验室条件下对K2CO_(3)吸附剂的CO_(2)吸附性能及SO_(2)对CO_(2)吸附的影响进行实验研究。结合XRD分析,利用密度泛函理论(densit... 电站锅炉的尾气在脱硫后含有微量的SO_(2),导致CO_(2)吸附剂性能变差。根据电厂烟气的组分,采用模拟烟气在实验室条件下对K2CO_(3)吸附剂的CO_(2)吸附性能及SO_(2)对CO_(2)吸附的影响进行实验研究。结合XRD分析,利用密度泛函理论(density functional theory,DFT)对SO_(2)在K2CO_(3)吸附剂上的影响及CO_(2)吸附机理进行理论研究。结果表明,受SO_(2)分子S原子活跃的s轨道影响,S的p轨道及O原子活性均增强,与K2CO_(3)表面O原子价带顶能带简并,SO_(2)被优先吸附在K2CO_(3)表面的O顶位,并将CO_(2)推离吸附剂表面,导致吸附剂活性位点虽有空余却无法吸附CO_(2)。在实验中表现为:模拟烟气中CO_(2)体积浓度为10%时,气氛中体积浓度为0.007%的SO_(2)会使吸附剂的吸附量由1.65 mmol/g降低至1.01 mmol/g。提出CO_(2)与H2O在K2CO_(3)(001)表面的吸附机理,理论计算的反应活化能为40.7 kJ/mol,反应热为-54.9 kJ/mol。 展开更多
关键词 K2CO_(3)吸附剂 CO_(2)捕集 SO_(2)影响 密度泛函理论 机理研究
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6-巯基-5-三唑并[4,3-b]-s-四嗪(MTT)的密度泛函理论研究
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作者 赵宁 陈慧 +2 位作者 任黎英 邵长斌 陈玉锋 《原子与分子物理学报》 CAS 北大核心 2024年第1期37-42,共6页
采用密度泛函理论(Density functional theory,DFT),在B3LYP/6-31g(d)(C,H,N,S),Ag原子采用LanL2d赝势基组水平上对甲醛(HCHO)与4-氨基-5肼基-3-巯基-1,2,4-三唑(4-amino-5-hydrazino-3-mercapto-1,2,4-triazole,AHMT)衍生化反应生的成... 采用密度泛函理论(Density functional theory,DFT),在B3LYP/6-31g(d)(C,H,N,S),Ag原子采用LanL2d赝势基组水平上对甲醛(HCHO)与4-氨基-5肼基-3-巯基-1,2,4-三唑(4-amino-5-hydrazino-3-mercapto-1,2,4-triazole,AHMT)衍生化反应生的成产物6-巯基-5-三唑并[4,3-b]-s-四嗪(6-mercapto-5-triazolo[4,3-b]-s-tetrazine,MTT)及其银配合物进行结构优化,优化结果表明MTT的结构是一个近平面结构.通过对频率计算,获得MTT分子及其银配合物的拉曼光谱,对400-1800 cm^(-1)波段内的拉曼光谱特征峰进行了指认.同时讨论了MTT分子的表面静电势,分析可能发生化学反应的位点.并采用含时密度泛函理论(Time Dependent density functional theory,TDDFT)对MTT分子与Ag3配合物的激发态进行了计算分析,并使用电荷转移光谱对Ag配合物与MTT之间电荷转移关系进行了研究.该研究对MTT分子的光谱测定和电子性质提供了理论基础. 展开更多
关键词 密度泛函理论 拉曼光谱 紫外光谱 6-巯基-5-三唑并[4 3-b]-s-四嗪
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基于DFT计算Cu掺杂γ-Fe_(2)O_(3)表面NH_(3)-SCR反应物吸附行为 被引量:1
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作者 李自朋 钟金钦 +2 位作者 王雪 郭健翔 任冬冬 《有色金属(冶炼部分)》 CAS 北大核心 2023年第11期86-95,112,共11页
NH_(3)-SCR脱硝技术由于其良好的脱硝效率及稳定性受到广泛应用,其核心是催化剂。γ-Fe_(2)O_(3)是一种具有良好低温脱硝活性的催化剂,采用Cu对其掺杂改性可有效提高其性能。为探究其反应机理,采用密度泛函理论(Density Function Theory... NH_(3)-SCR脱硝技术由于其良好的脱硝效率及稳定性受到广泛应用,其核心是催化剂。γ-Fe_(2)O_(3)是一种具有良好低温脱硝活性的催化剂,采用Cu对其掺杂改性可有效提高其性能。为探究其反应机理,采用密度泛函理论(Density Function Theory,DFT)方法对SCR反应过程中NH_(3)、NO、O_(2)等反应物分子在Cu掺杂γ-Fe_(2)O_(3)催化剂表面的吸附行为进行研究。结果表明,NH_(3)、NO、O_(2)均会吸附在Cu、Fe两个活性位点上,并形成稳定的吸附构型。在NH 3吸附过程中,NH_(3)会失去电子,N原子与Fe、Cu形成稳定的化学键。NO以N原子端靠近催化剂表面时,主要发生化学吸附,而以O原子靠近时发生物理吸附。NO主要表现为失去电子,当以N原子吸附时形成了稳定的化学键。O_(2)吸附时会得到电子并与金属离子之间形成稳定的化学吸附构型。在吸附过程中,小分子吸附于Fe活性位上时较为稳定。 展开更多
关键词 NH_(3)-SCR 密度泛函理论(dft) Cu γ-Fe_(2)O_(3) 吸附
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B_(3)N_(3)H_(6)…CO复合物中弱相互作用竞争的理论研究
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作者 奥美珍 闫苗 +1 位作者 马媛媛 石佳 《化学研究与应用》 CAS 北大核心 2023年第4期870-877,共8页
本文在MP2/aug-cc-pVTZ水平下对一氧化碳(CO)和环硼氮烷(B_(3)N_(3)H_(6))之间的弱相互作用进行理论研究,得到6种稳定的B_(3)N_(3)H_(6)…CO复合物结构。B_(3)N_(3)H_(6)…CO复合物中存在N—H…C/O氢键以及π…π、lp…π相互作用,其中... 本文在MP2/aug-cc-pVTZ水平下对一氧化碳(CO)和环硼氮烷(B_(3)N_(3)H_(6))之间的弱相互作用进行理论研究,得到6种稳定的B_(3)N_(3)H_(6)…CO复合物结构。B_(3)N_(3)H_(6)…CO复合物中存在N—H…C/O氢键以及π…π、lp…π相互作用,其中含N—H…C氢键复合物的相互作用能(ΔE)最大,为-1.42 kcal·mol^(-1)。系统的理论计算结果表明π…π相互作用和N—H…C/O氢键可以成功地与lp…π相互作用竞争。取代基效应结果显示,B3N3X3H3(X=-NH2)…CO、B_(3)N_(3)H_(6)…CO、B3N3X3H3(X=-F)…CO中π…π相互作用的ΔE依次减小,分别为-1.84、-1.29和-1.17 kcal·mol^(-1)。AIM分析揭示了B_(3)N_(3)H_(6)…CO复合物中lp…π、π…π相互作用以及N—H…C/O氢键的本质。SAPT能量分解分析结果表明含N—H…C/O氢键的复合物I和IV中静电作用和色散作用对结构的稳定同样重要,而色散作用对含π…π和lp(O/C)…π相互作用的复合物II、III和V、VI的结构稳定起主要作用。该研究为认识生物分子中杂环芳香环与羰基之间的相互作用提供理论研究。 展开更多
关键词 环硼氮烷 一氧化碳 分子间相互作用 竞争 密度泛函理论
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A Periodic Density Functional Study on Adsorption Properties of Methoxy on Au(111) Surface 被引量:2
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作者 刘书红 陈文凯 +3 位作者 曹梅娟 陆春海 许莹 李俊篯 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2006年第1期53-58,共6页
Adsorption of CH3O at four sites (top, bridge, hcp, fcc) on Au(111) surface has been investigated by density functional theory method at the generalized gradient approximation level. We have performed calculations... Adsorption of CH3O at four sites (top, bridge, hcp, fcc) on Au(111) surface has been investigated by density functional theory method at the generalized gradient approximation level. We have performed calculations on adsorption energies, structures, Mulliken charges and vibrational frequencies of CH3O on Au(111) surface with full-geometry optimization. The predicted results are compared with the available experimental observation. The calculated CH3O adsorption structure and stretching vibrational frequencies agree well with experimental ones, and precise determinations of adsorption sites are carded out. The most favorite adsorption on Au(111) occurs at the bridge site, and O-C axis is tilted to the surface. However, on hollow sites (hcp, fcc) the species is adsorbed in an upright geometry (pseudo-C3v local symmetry). 展开更多
关键词 density functional theory (dft Au(111) surface CH3O ADSORPTION
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First Principles Investigation of the Structure and Properties of Superconducting Cubic Protactinium Hydride PaH3
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作者 Tao Liu Tao Gao 《Journal of Applied Mathematics and Physics》 2023年第4期1113-1123,共11页
Cubic protactinium hydrides are very important existing form in superconducting protactinium hydrogen series. In this work, the ground state structure and properties of cubic PaH<sub>3</sub> have been stud... Cubic protactinium hydrides are very important existing form in superconducting protactinium hydrogen series. In this work, the ground state structure and properties of cubic PaH<sub>3</sub> have been studied using the DFT + U method. This systematic study for two bulk properties includes the electronic structures, phonon dispersion curves, structural, mechanical and thermodynamic properties under the effective coulomb U and exchange J PBE + U parameters. Structural relaxation results show that the Pa-H and Pa-Pa distances in α-PaH<sub>3</sub> are significantly higher than that in β-PaH<sub>3</sub>, and the H-H distances in α-PaH<sub>3</sub> are slightly smaller than that in β-PaH<sub>3</sub>. For the ground state electronic structures of α-PaH<sub>3</sub> and β-PaH<sub>3</sub>, we found that α-PaH<sub>3</sub> and β-PaH<sub>3</sub> are metallic, and the protactinium 5f electronic states and hydrogen have obvious bonding effect, resulting in weakening of the material’s metallicity. This is consistent with observations for the other actinide hydrides such as ThH<sub>3</sub> and UH<sub>3</sub>. The phonon spectrum calculations reveal that the PBE and PBE + U methods give quite different frequencies for the optical branches of phonons of α-PaH<sub>3</sub> and β-PaH<sub>3</sub>. In addition, by including the vibrational entropy and the ZPE using the phonon frequencies obtained from the optimized unit cells we predict that the β-PaH<sub>3</sub> phase can not transit into α-PaH<sub>3</sub> phase above room temperature. 展开更多
关键词 α-PaHb>3b> and β-PaHb>3b> Electronic Properties Mechanical Properties Thermodynamic Properties density functional theory (dft)
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DFT Calculations for Electron Transfer Bond-breakingReaction of CH_3-X
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作者 Yu Mei XING Zheng Yu ZHOU Ben Ni DU 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第4期347-350,共4页
DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Throug... DFT/6-311 + g** level calculations are performed tp study the electron transfer bond-breaking reaction of CH3-X. The calculated values are in good agreement with the experimental results or the empirical model. Through analyzing the change of the energy and the charge densilty along hte reaction path, the bond-breaking in ET reaction for CH3X is investigated. 展开更多
关键词 electron transfer bond-breaking reaction density functional theory (dft) CH_(3)X
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Assessment of Advanced xDH@B3LYP Methods in Describing Various Potential Energy Curves Driven byπ-π,CH/π,and SH/πNon-Bonded Interactions
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作者 Shiqian Tan Yizhen Wang +1 位作者 Igor Ying Zhang Xin Xu 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第5期720-726,I0011,共8页
Accurate description of potential energy curves driven by nonbonded interactions remains a great challenge for pure density functional approximations(DFAs).It is because the Rdecay behavior of dispersion cannot be int... Accurate description of potential energy curves driven by nonbonded interactions remains a great challenge for pure density functional approximations(DFAs).It is because the Rdecay behavior of dispersion cannot be intrinsically captured by the(semi)-local ingredients and the exact-exchange used in the popular hybrid DFAs.Overemphasizing the accuracy on the equilibrium region for the functional construction would likely deteriorate the overall performance on the other regions of potential energy surfaces.In consequence,the empirical dispersion correction becomes the standard component in DFAs to treat the non-bonded interactions.In this Letter,we demonstrate that without the use of empirical dispersion correction,doubly hybrid approximations,in particular two recently proposed rev XYG3 and XYG7 functionals,hold the promise to have a balanced description of non-bonded interactions on the whole potential energy curves for several prototypes ofπ-π,CH/π,and SH/πinteractions.The error of rev XYG3 and XYG7 for non-bonded interactions is around 0.1 kcal/mol,and their potential energy curves almost coincide with the accurate CCSD(T)/CBS curves. 展开更多
关键词 density functional theory Non-bonded interaction Doubly hybrid approximations xDH@b3lyp model
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Electronic Absorption Spectra and Third-Order Nonlinear Optical Property of Dinaphtho[2,3-b:2’,3’-d]Thiophene-5,7,12,13- Tetraone (DNTTRA) and Its Phenyldiazenyl Derivatives: DFT Calculations
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作者 Ziran Chen Yujin Zhang +3 位作者 Zhanrong He Yonghua Guan Yuan Li Hongping Li 《Computational Chemistry》 2020年第4期43-60,共18页
Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of... Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained. 展开更多
关键词 AZObENZENE Dinaphtho[2 3-b:2’ 3’-d]Thiophene-5 7 12 13-Tetraone density functional theory Electronic Absorption Spectra Third-Order Nonlinear Optical Property
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Co-Fe-B非晶态合金成键及电子性质的DFT研究
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作者 张成刚 方志刚 +4 位作者 赵振宁 韩建明 刘继鹏 徐诗浩 刘琪 《河南师范大学学报(自然科学版)》 CAS 北大核心 2016年第6期96-102,共7页
利用密度泛函理论(DFT),通过团簇Co2FeB2,CoFe2B2的优化和计算,研究Co-Fe-B非晶态合金成键及电子性质.结果表明:团簇Co2FeB2(富Co)中主要的电子流向为B→Co,B→Fe,而团簇CoFe2B2(富Fe)电子流向多样化,这导致富Co合金中键级比例分布不均... 利用密度泛函理论(DFT),通过团簇Co2FeB2,CoFe2B2的优化和计算,研究Co-Fe-B非晶态合金成键及电子性质.结果表明:团簇Co2FeB2(富Co)中主要的电子流向为B→Co,B→Fe,而团簇CoFe2B2(富Fe)电子流向多样化,这导致富Co合金中键级比例分布不均匀,而富Fe合金中键级比例相对均匀;另外,金属与B原子成键对合金稳定性的贡献最大,而两种团簇的M(max)-B与Co-Fe键协同作用相反:富Co团簇中Co-B与Co-Fe成键强度同增同长,而富Fe团簇中Fe-B与Co-Fe成键强度相互抑制.以上结论在一定程度上解释了富Co合金热稳定性差的现象.另外,B原子使富Fe团簇空间结构、成键以及电子流动方向更加复杂,使合金非晶态化增加.Co-Fe-B非晶态合金中存在B原子之间近距离接触,希望此结论不久后得到实验验证. 展开更多
关键词 Co-Fe-b非晶态合金 局域结构 成键性质 电子性质 稳定性 密度泛函理论(dft)
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簇合物(Me_2BN_3)_n(n=1~3)结构和性质的理论研究
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作者 夏其英 马登学 《临沂师范学院学报》 2010年第3期90-95,共6页
采用密度泛函理论B3LYP/6—311+G^6方法,计算研究了(Me2BN3)n(n=1~3)簇合物的结构和性质.研究表明,环状多聚体(Me2BN3)n(n=1~3)的优化构型均为由不同子体系的叠氮基0-N和B原予相连形成的环状结构.讨论几何参数随聚合度... 采用密度泛函理论B3LYP/6—311+G^6方法,计算研究了(Me2BN3)n(n=1~3)簇合物的结构和性质.研究表明,环状多聚体(Me2BN3)n(n=1~3)的优化构型均为由不同子体系的叠氮基0-N和B原予相连形成的环状结构.讨论几何参数随聚合度的变化关系,同时对所有优化构型进行振动频率计算,对其IR谱进行归属,并与实验值进行了比较,结果发现计算值均可信.簇合物的热力学函数均随簇合物的聚合度n以及温度的增加而呈线性增加.由聚合反应的焓变可知,在298.2K下单体形成三聚体在热力学上是有利的,而形成二聚体则是不利的. 展开更多
关键词 (Me2bN3)n(n=1~3) 密度泛函理论 结构特色 IR谱 热力学性质
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Synthesis,Crystal Structure and Spectroscopic Properties of 1,2-Benzothiazine Derivatives:An Experimental and DFT Study 被引量:1
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作者 MUHAMMAD Nadeem Arshad TARIQ Mahmood +7 位作者 ATHER Faroque Khan MUHAMMAD Zia-Ur-Rehman ABDULLAH M.Asiri ISLAM Ullah Khan RIFFAT-Un-Nisa KHURSHID Ayub AZAM Mukhtar MUHAMMAD Tariq Saeed 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2015年第1期15-25,共11页
1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide(1) and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxid... 1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide(1) and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxide(2) were synthesized, and characterized by spectroscopic techniques; 1H-NMR and infrared(IR) spectroscopy. Crystals of 1 and 2 were grown by slow evaporation of methanol and ethyl acetate, respectively and their crystal structures were investigated by single-crystal X-ray diffraction analysis. Geometric properties were calculated by the B3 LYP method of density functional theory(DFT) at the 6-31G+(d) basis set to compare with the experimental data. Simulated properties were found in strong agreement with the experimental ones. Intermolecular forces have also been modeled in order to investigate the strength of packing and strong hydrogen bonding was observed in both compounds 1 and 2. Electronic properties such as Ionization Potential(IP), Electron Affinities(EA) and coefficients of the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) of com- pounds 1 and 2 were simulated for the first time. 展开更多
关键词 1 2-benzothiazine b3lyp/6-31+G (d) density functional theory (dft HUMO-LUMO crystal structures
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共掺杂TiO_2-B作为可充电锂离子电池负极材料的DFT+U分析
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作者 庞可 孔令明 +1 位作者 任瑞鹏 吕永康 《太原理工大学学报》 北大核心 2017年第6期901-906,共6页
采用多元胞组合法构建出钝化共掺杂TiO_2-B模型,并引入共掺杂原子N+V和C+Cr,对其进行第一性原理的密度泛函理论(density functional theory,DFT)分析。通过对Li^+嵌入位点和迁移活化能的计算,确定了Li^+低浓度下共掺杂模型中最稳定的嵌... 采用多元胞组合法构建出钝化共掺杂TiO_2-B模型,并引入共掺杂原子N+V和C+Cr,对其进行第一性原理的密度泛函理论(density functional theory,DFT)分析。通过对Li^+嵌入位点和迁移活化能的计算,确定了Li^+低浓度下共掺杂模型中最稳定的嵌入位点,得出N+V和C+Cr共掺杂体系的迁移活化能分别为0.47,0.42eV;对Li^+高浓度下嵌入电压进行计算,得出N+V共掺杂嵌入电压为0.83~0.97V,比C+Cr共掺杂的对应值1.05~1.27V小,因此N+V共掺杂模型更适合用作锂离子电池的负极材料;对两种共掺杂的态密度进行计算,得出N+V和C+Cr共掺杂体系的带隙宽度分别为1.7,1.4eV,说明N和C主要修饰价带结构,V和Cr主要修饰导带结构。 展开更多
关键词 Li离子电池 负极材料 TiO2-b 钝化共掺杂 嵌入电压 迁移活化能 带隙 密度泛函理论
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Selective Sensing Characteristics of Ca Doped BeO Nano-sized Tube toward H20 and NH3
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作者 Maziar Noei Vali Zare-Shahabadi Seyedeh Najmeh Razi 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第5期612-616,I0004,共6页
By means of density functional calculations, the structural and electronic properties of chemical modification of pristine and Ca-doped BeO nanotubes were investigated with NH3 and H20 molecules. It was found that the... By means of density functional calculations, the structural and electronic properties of chemical modification of pristine and Ca-doped BeO nanotubes were investigated with NH3 and H20 molecules. It was found that the NH3 and H20 molecules can be adsorbed on the Be atom of the tube sidewall with the adsorption energies of about 36.1 and 39.0 kcal/mol, respectively. Density of states analysis shows that the electronic properties of the BeONT are slightly changed after the adsorption processes. Substitution of a Be atom in the tube surface with a Ca atom increases the adsorption energies by about 7.4 and 14.7 kcal/mol for NH3 and H20, respectively. Unlike the pristine tube, the electronic properties of Ca-doped BeONT are sensitive to NH3 and H20 molecules. Also, the Ca-doped tube is much more sensitive to H20 molecule than NH3 one. 展开更多
关键词 Doping density functional theory Sensor b3lyp
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Na_(2)MnPO_(4)F/Ti_(3)C_(2)-CQDs对Li/Na储能性能的密度泛函理论研究
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作者 王绍聪 李伟 +1 位作者 周烽海 刘峥 《电池》 CAS 北大核心 2023年第6期624-628,共5页
Na_(2)MnPO_(4)F作为锂/钠混合离子电池的电极材料,具有低成本、无毒、高电压和价态丰富等特点,但电子电导率低、离子扩散速率慢、锰的溶解及Jahn-Teller效应,限制了其应用。基于密度泛函理论下的第一性原理,以Na_(2)MnPO_(4)F/Ti_(3)C_... Na_(2)MnPO_(4)F作为锂/钠混合离子电池的电极材料,具有低成本、无毒、高电压和价态丰富等特点,但电子电导率低、离子扩散速率慢、锰的溶解及Jahn-Teller效应,限制了其应用。基于密度泛函理论下的第一性原理,以Na_(2)MnPO_(4)F/Ti_(3)C_(2)和Na_(2)MnPO_(4)F/Ti_(3)C_(2)-碳量子点(CQDs)复合材料为研究对象,构建Na2MnPO4F、NaLiMnPO_(4)F、Na_(2)MnPO_(4)F/Ti_(3)C_(2)、NaLiMnPO_(4)F/Ti_(3)C_(2)、Na_(2)MnPO4F/Ti_(3)C_(2)-CQDs和NaLiMnPO_(4)F/Ti_(3)C_(2)-CQDs等6种结构模型,计算能带结构、结合能、态密度及电荷局域密度,分析复合前后材料的电子结构和性能变化。Li原子的引入,使Na_(2)MnPO_(4)F与Ti_(3)C_(2)和Ti_(3)C_(2)-CQDs的结合能分别增大1.1397 J/m^(2)和0.7866 J/m^(2),复合Ti_(3)C_(2)和Ti_(3)C_(2)-CQDs能改善Na_(2)MnPO_(4)F的导电性,且Ti_(3)C_(2)-CQDs改善效果更佳。 展开更多
关键词 Na_(2)MnPO_(4)F Ti_(3)C_(2)-碳量子点(CQDs)复合材料 第一性原理 密度泛函理论(dft)
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The electronic structures, Born effective charge tensors,and phonon properties of cubic, tetragonal,orthorhombic, and rhombohedral K_(0.5)Na_(0.5)NbO_3: A first-principles comparative study
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作者 周树兰 赵显 +1 位作者 江向平 韩晓东 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第12期390-397,共8页
The electronic structures, Born effective charges(BECs), and full phonon dispersions of cubic, tetragonal, orthorhombic, and rhombohedral K0.5Na0.5Nb O3 are investigated by the first principles method based on densi... The electronic structures, Born effective charges(BECs), and full phonon dispersions of cubic, tetragonal, orthorhombic, and rhombohedral K0.5Na0.5Nb O3 are investigated by the first principles method based on density functional theory.The hybridized states of Nb 4d and O 2p states are observed in the valence band, showing the formation of a strong Nb–O covalent bond which should be responsible for the displacement of Nb and O atoms. The abnormally large BECs of Nb and O indicate the possibility of phase instability induced by the off-center displacement of Nb and O atoms. The phonon dispersions reveal that the ferroelectric instability of K0.5Na0.5Nb O3 is dominated by Nb and O displacements with significant Na characteristics. In addition to the ferroelectric instability, there is also rotational instability coming from the oxygen octahedra rotation around one axis. Moreover, the Γ phonon properties of orthorhombic KNb O3, Na Nb O3, and K0.5Na0.5Nb O3 are also studied in detail. 展开更多
关键词 born effective charge phonon dispersion density functional theory(dft phase instability of K0.5Na0.5NbO3
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First Principle Study of the Structural and Piezoelectric Properties of Perovskite ZrTi(PbO<sub>3</sub>)<sub>2</sub>Materials for Naval SONAR
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作者 Owolabi Joshua Adeyemi Gidado Mohammed Mawashi +2 位作者 Alhassan Shuaibu Bamikole Johnson Akinade Ugbe Raphael Ushiekpan 《Journal of Applied Mathematics and Physics》 2019年第2期271-280,共10页
First principle calculation within the Density Functional Theory (DFT) and Density Functional Perturbation Theory (DFPT) using Local Density Approximation as implemented in Quantum ESPRESSO has been significantly used... First principle calculation within the Density Functional Theory (DFT) and Density Functional Perturbation Theory (DFPT) using Local Density Approximation as implemented in Quantum ESPRESSO has been significantly used to investigate the structural and Piezoelectric, properties of Perovskite ZrTi(PbO3)2. From structural properties calculation, the ground state total energy of -2417.12 eV has been obtained which led to an equilibrium lattice constant of a= 5.620&#197;for ZrTi(PbO3)2. Our obtained optimized atomic positions and atomic effective charge shows that the optimized ZrTi(PbO3)2 is stable and the Piezoelectric stress tensor is calculated using Berry-phase approach within density functional perturbation theory (DFPT). From our calculation, we have obtained the stress tensor elements with values of d1,5 = 6.81, d3,1 = 1.69, and d3,3 = 6.18, which is in agreement with the values obtained for tetragonal PbTiO3. 展开更多
关键词 STRUCTURAL Properties PEROVSKITE ZrTi(PbO3)2 density functional theory (dft) density functional Perturbation theory (DFPT) Local density Approximation (LDA)
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DFT Study of Geometrical and Vibrational Features of Sulfur Containing Amino Acids in Hydrated Media: L-Cysteine and L-Methionine
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作者 Mama Nsangou Jonathan Koyambo-Konzapa Jean Jules Fifen 《Journal of Chemistry and Chemical Engineering》 2013年第9期850-871,共22页
Geometry optimization at the B3LYP/6-31++G* level of theory has been undertaken on clusters containing L-Met (L-methionine) or L-Cys (L-cysteine) surrounded by eight water molecules. The comparison of the struc... Geometry optimization at the B3LYP/6-31++G* level of theory has been undertaken on clusters containing L-Met (L-methionine) or L-Cys (L-cysteine) surrounded by eight water molecules. The comparison of the structural parameters of L-Met and L-Cys with X-ray experimental values is in good agreement within 4.8%. This result shows that the privileged positions of water molecules and the possible hydrogen bonding network formed around the backbone of both AAs (amino acids) are adequate. Subsequent calculations of the harmonic vibrational modes followed by a post-processing treatment enable us to assign the vibrational modes of L-Met and L-Cys surrounded explicitly by eight water molecules. The frequencies of the assigned modes are in good agreement with available IR (infra red) and Raman values within 5%. 展开更多
关键词 dft density functional theory 6-3 1++G(d) sufur containing amino-acids METHIONINE cysteine explicit solvation.
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密度泛函理论研究不对称簇合物(CH_(3)BrBN_(3))_(n)(n=1-6)的结构和稳定性
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作者 马登学 刘国魁 +1 位作者 夏其英 宋兴良 《原子与分子物理学报》 CAS 北大核心 2021年第1期63-69,共7页
为了寻求制备BN材料的单一源前驱体,用密度泛函理论DFT方法计算研究不对称簇合物(CH_(3)BrBN_(3))_(n)(n=1-6)的几何构型、相对稳定性和热力学性质.当n≥2时,B原子和Nα原子容易成键,形成环状结构.通过计算分析体系的二阶差分能量而判... 为了寻求制备BN材料的单一源前驱体,用密度泛函理论DFT方法计算研究不对称簇合物(CH_(3)BrBN_(3))_(n)(n=1-6)的几何构型、相对稳定性和热力学性质.当n≥2时,B原子和Nα原子容易成键,形成环状结构.通过计算分析体系的二阶差分能量而判断其相对稳定性.分析温度对体系热力学函数的影响,由焓变可知,室温下由单体形成稳定的多聚体(CH_(3)BrBN_(3))_(n)(n=2-6)在热力学上有利.同时,探讨了簇合物尺寸大小对结构和性质的影响.这些结果将有助于设计和合成其它不对称叠氮硼类簇合物. 展开更多
关键词 不对称簇合物(CH_(3)brbN_(3))_(n)(n=1-6) 密度泛函理论 稳定性 热力学性质 尺寸效应
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