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Impedance spectroscopy and DFT/TD-DFT studies of diyttrium trioxide for optoelectronic fields 被引量:1
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作者 Ali A.Alkathiri A.A.Atta +7 位作者 Moamen S.Refat Sonam Shakya A.M.Hassanien Saud A.Algarni Emad M.A.Ahmed Sultan E.Alomariy Mohammed Alsawat Norah Algethami 《Journal of Rare Earths》 SCIE EI CAS CSCD 2023年第4期605-612,共8页
Yttrium(Ⅲ)oxide or so-called diyttrium trioxide(Y_2O_3)is an excellent candidate ceramic material for optoelectronic applications.Structural,electrical conductivity,and dielectric relaxation properties of bulk yttri... Yttrium(Ⅲ)oxide or so-called diyttrium trioxide(Y_2O_3)is an excellent candidate ceramic material for optoelectronic applications.Structural,electrical conductivity,and dielectric relaxation properties of bulk yttrium(Ⅲ)oxide were studied.X-ray diffraction(XRD)results indicate that the yttrium(Ⅲ)oxide compound has a crystalline cubic phase.Fourier transform infrared(FTIR)technique was used to ascertain the chemical structure of the yttrium(Ⅲ)oxide compound.Impedance spectroscopy was used to analyze frequency-dependent electrical properties as a function of temperature in the range of 303-423 K and frequency range of 0.1 Hz-2 MHz.Impedance spectroscopy parameters such as dielectric constant,dielectric loss,loss factor,electric modulus,and complex impedance of the yttrium(Ⅲ)oxide compound were studied.The Nyquist plot describes the complex impedance of the yttrium(Ⅲ)oxide for different temperatures.The universal Jonscher's power law was used for the analysis of the complex electrical conductivity of the yttrium(Ⅲ)oxide compound.It is found that the real(σ')and imaginary(σ")parts of the complex conductivity increase with increasing frequency.The exponent frequency(s)equals unity,which confirms that the predominant conduction mechanism is a nearly constant loss(NCL)mechanism.DFT/TD-DFT studies using B3LYP/LanL2DZ level of theory were used to provide comparable theoretical data and electronic energy gap of HOMO→LUMO. 展开更多
关键词 Yttrium(Ⅲ)oxidel Impedance spectroscopy dft/td-dft Rare earths
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Investigation of the Spin Crossover Complex [Fe(bapbpy)(NCS)_2 ] in Its Low-spin and Highspin State by DFT/TD-DFT/BS-DFT Calculations 被引量:1
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作者 曲玉辉 黎乐民 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2013年第9期1279-1290,共12页
The spin crossover(SCO) compound [Fe(bapbpy)(NCS)2],where bapbpy contains two fused N,N-bis(2-pyridyl)amines,has been studied by DFT/TD-DFT/BS-DFT methods.Several density functionals and basis sets were used i... The spin crossover(SCO) compound [Fe(bapbpy)(NCS)2],where bapbpy contains two fused N,N-bis(2-pyridyl)amines,has been studied by DFT/TD-DFT/BS-DFT methods.Several density functionals and basis sets were used in the calculation to obtain optimized geometries of the compound in the low-(LS) and high-spin(HS) states.The vibrational modes and IR spectra,spin splitting energies,excited states and UV/Vis absorption spectra were obtained.The structural parameters of the calculated isolated complex are in good agreement with the X-ray data.We investigate three dimers of [Fe(bapbpy)(NCS)2] complex for their magnetic properties.It has been found that the complex(1,3) has ferromagnetic character while the others are antiferromagnetic in nature by using a broken symmetry approach in the DFT framework(BS-DFT) with support from the coupling constant values(J) and spin density plots. 展开更多
关键词 spin crossover dft vibrations and IR spectra excited states and UV/vis absorption spectra coupling constant values(J)
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A DFT/TD-DFT study of effect of different substituent on ESIPT fluorescence features of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole derivatives
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作者 Shen-Yang Su Xiu-Ning Liang Hua Fang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第3期589-596,共8页
Based on density functional theory(DFT) and time-dependent density functional theory(TD-DFT), the effects of substituent on the excited-state intramolecular proton transfer(ESIPT) process and photophysical properties ... Based on density functional theory(DFT) and time-dependent density functional theory(TD-DFT), the effects of substituent on the excited-state intramolecular proton transfer(ESIPT) process and photophysical properties of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole(HCT) are studied. The electron-donating group(CH_(3), OH) and electronwithdrawing group(CF_(3), CHO) are introduced to analyze the changes of intramolecular H-bond, the frontier molecular orbitals, the absorption/fluorescence spectra, and the energy barrier of ESIPT process. The calculation results indicate that electron-donating group strengthens the intramolecular H-bond in the S_(1) state, and leads to an easier ESIPT process. The electron-withdrawing group weakens the corresponding H-bond and makes ESIPT process a little harder. Different substituents also affect the photophysical properties of HCT. The electron-withdrawing group(CF_(3), CHO) has a little effect on electronic spectra. The electron-donating group(CH_(3), OH) red-shifts both the absorption and fluorescence emission peaks of HCT, respectively, which causes the Stokes shift to increase. 展开更多
关键词 excited-state intramolecular proton transfer(ESIPT) td-dft SUBSTITUTION
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Spectroscopic Characterization, Molecular Modeling and DFT/TD-DFT/PCM Calculations of Novel Hydrogen-Bonded Charge Transfer Complex between Chloranilic Acid and 2-Amino-4,6-Dimethylpyridine
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作者 Khairia M. Al-Ahmary Fatimah A. Alshehri +1 位作者 Faten M. Atlam Mohamed K. Awad 《Open Journal of Physical Chemistry》 2020年第1期1-32,共32页
A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimen... A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation. 展开更多
关键词 2-Amino-4 6-Dimethylpyridine Charge Transfer dft Hydrogen BOND Molecular Modelling COMPUTATIONS and Spectroscopy
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硫铁化合物自燃影响因素及自燃机制的DFT研究综述
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作者 武司苑 陈天昊 +3 位作者 张钰 申青春 朱建文 史柏超 《安全与环境工程》 北大核心 2026年第1期156-168,共13页
硫铁化合物自燃是炼油行业长期面临的重要安全问题,尤其在处理高含硫原油时更为突出。从宏观影响因素和微观反应机理2个维度进行综述。在宏观层面,分析了温度、氧气浓度、湿度、粒径和化学组分等因素对硫铁化合物自燃的影响规律,以及多... 硫铁化合物自燃是炼油行业长期面临的重要安全问题,尤其在处理高含硫原油时更为突出。从宏观影响因素和微观反应机理2个维度进行综述。在宏观层面,分析了温度、氧气浓度、湿度、粒径和化学组分等因素对硫铁化合物自燃的影响规律,以及多因素耦合时硫铁化合物的自燃风险;在微观层面,以密度泛函理论(density functional theory,DFT)为基础,深入分析总结了硫铁化合物的电子结构特征、表面吸附行为和化学反应路径等微观机理。最后指出了当前研究在材料代表性、多场景适用性和反应机理认识等方面存在的问题,并提出了建议,旨在为硫铁化合物自燃防控提供更完善的理论基础和技术支撑。 展开更多
关键词 硫铁化合物 自燃 影响因素 密度泛函理论(dft)
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基于DFT计算的Cu掺杂CePO_(4)-H表面NH_(3)-SCR吸附行为研究
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作者 唐明轩 赵然 +2 位作者 潘东明 赵增武 刘畅 《稀有金属与硬质合金》 北大核心 2026年第1期83-92,107,共11页
Ce基催化剂拥有较高的氧储存能力和良好的高温热稳定性,在脱硝反应中展现出突出性能。针对CePO_(4)-H(六方磷酸铈)催化剂中Ce位点对NH_(3)和NO分子的低温吸附活性偏低的问题,本文采用浸渍法制备了Cu掺杂的CePO_(4)-H催化剂,研究了不同C... Ce基催化剂拥有较高的氧储存能力和良好的高温热稳定性,在脱硝反应中展现出突出性能。针对CePO_(4)-H(六方磷酸铈)催化剂中Ce位点对NH_(3)和NO分子的低温吸附活性偏低的问题,本文采用浸渍法制备了Cu掺杂的CePO_(4)-H催化剂,研究了不同Cu含量对催化剂脱硝性能和物相组成的影响;基于第一性原理密度泛函理论(DFT),采用PBE泛函研究了Cu掺杂CePO_(4)-H(100)晶面对NH_(3)-SCR反应中NH_(3)和NO的吸附行为。实验结果表明,Cu掺杂前后CePO_(4)-H催化剂均呈现典型六方相CePO_(4)特征;掺杂Cu后,CePO_(4)-H催化剂的NOx转化率提升,活性温度窗口变宽,NH_(3)-SCR催化脱硝性能明显提升。理论研究结果表明,NH_(3)和NO分子均能在Cu掺杂的CePO_(4)-H催化剂的Ce和Cu活性位点吸附,且无论是NH_(3)分子还是NO分子,在Ce活性位点上的吸附构型均表现出更高的稳定性。相较于未掺杂的CePO_(4)-H催化剂,Cu的掺杂显著增强了催化剂对NO的化学吸附能力,而对NH_(3)的吸附能力提升幅度相对较小。Cu活性位点吸附NH_(3)时为物理吸附,而吸附NO时发生典型的化学吸附。Cu掺杂通过调控CePO_(4)-H催化剂表面的电子结构,提高了反应物分子的吸附能,进而显著提高了NH_(3)-SCR反应的催化活性。本研究为CePO_(4)-H催化剂NH_(3)-SCR脱硝性能的提升提供了实验数据和理论支撑。 展开更多
关键词 dft NH_(3)-SCR CU掺杂 CePO_(4)-H 催化剂吸附 脱硝性能 活性位点
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基于DFT重构的改进i_(p)-i_(q)基波正序有功和无功电流检测算法
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作者 李锦彬 朱罗翔 《电气应用》 2026年第1期133-140,共8页
针对传统硬件锁相环i_(p)-i_(q)算法无法实现基波正序有功与无功电流分离的问题,提出了一种基于DFT重构的改进i_(p)-i_(q)检测算法。该算法通过DFT实现αβ轴系下基波电压及其正交量的重构,结合瞬时对称分量变换,完成基波正序、负序电... 针对传统硬件锁相环i_(p)-i_(q)算法无法实现基波正序有功与无功电流分离的问题,提出了一种基于DFT重构的改进i_(p)-i_(q)检测算法。该算法通过DFT实现αβ轴系下基波电压及其正交量的重构,结合瞬时对称分量变换,完成基波正序、负序电压的解耦,为i_(p)-i_(q)算法提供准确的电压相位信息,从而实现基波正序有功、无功电流的检测。与传统的i_(p)-i_(q)法相比,所提改进算法采用数字锁相环,有效解决了电网复杂工况下的电压相位跟踪问题,可准确、快速地提取基波正序有功和无功电流。最后通过仿真和实验验证了该算法的正确性。 展开更多
关键词 锁相环 i_(p)-i_(q)算法 dft重构 瞬时对称分量法 基波正序有功电流
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DFT Insights into the Detection of NH_(3),AsH_(3),PH_(3),CO_(2),and CH_(4)Gases with Pristine and Monovacancy Phosphorene Sheets
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作者 Naresh Kumar Anuj Kumar Abhishek K.Mishra 《Computers, Materials & Continua》 2026年第4期517-531,共15页
Density functional theory(DFT)calculations were employed to investigate the adsorption behavior of NH_(3),AsH_(3),PH_(3),CO_(2),and CH_(4)molecules on both pristine and mono-vacancy phosphorene sheets.The pristine pho... Density functional theory(DFT)calculations were employed to investigate the adsorption behavior of NH_(3),AsH_(3),PH_(3),CO_(2),and CH_(4)molecules on both pristine and mono-vacancy phosphorene sheets.The pristine phosphorene surface showsweak physisorption with all the gasmolecules,inducing onlyminor changes in its structural and electronic properties.However,the introduction ofmono-vacancies significantly enhances the interaction strength with NH_(3),PH_(3),CO_(2),and CH_(4).These variations are attributed to substantial charge redistribution and orbital hybridization in the presence of defects.The defective phosphorene sheet also exhibits enhanced adsorption energies,along with favorable sensitivity and recovery characteristics,highlighting its potential as a promising gas sensor for NH_(3),AsH_(3),PH_(3),CO_(2),and CH_(4)at ambient conditions. 展开更多
关键词 Phosphorene VACANCY defects dft interaction sensitivity
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Data-driven insights into nonradical activation mechanisms for biochar inverse design:A synergistic approach using DFT and machine learning with meta-analysis
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作者 Honglin Chen Rupeng Wang +1 位作者 Zixiang He Shih-Hsin Ho 《Chinese Chemical Letters》 2026年第2期708-712,共5页
Machine learning(ML)is recognized as a potent tool for the inverse design of environmental functional material,particularly for complex entities like biochar-based catalysts(BCs).Thus,the tailored BCs can have a disti... Machine learning(ML)is recognized as a potent tool for the inverse design of environmental functional material,particularly for complex entities like biochar-based catalysts(BCs).Thus,the tailored BCs can have a distinct ability to trigger the nonradical pathway in advance oxidation processes(AOPs),promising a stable,rapid and selective degradation of persistent contaminants.However,due to the inherent“black box”nature and limitations of input features,results and conclusions derived from ML may not always be intuitively understood or comprehensively validated.To tackle this challenge,we linked the front-point interpretable analysis approaches with back-point density functional theory(DFT)calculations to form a chained learning strategy for deeper sight into the intrinsic activation mechanism of BCs in AOPs.At the front point,we conducted an easy-to-interpret meta-analysis to validate two strategies for enhancing nonradical pathways by increasing oxygen content and specific surface area(SSA),and prepared oxidized biochar(OBC500)and SSA-increased biochar(SBC900)by controlling pyrolysis conditions and modification methods.Subsequently,experimental results showed that OBC500 and SBC900 had distinct dominant degradation pathways for 1O2 generation and electron transfer,respectively.Finally,at the end point,DFT calculations revealed their active sites and degradation mechanisms.This chained learning strategy elucidates fundamental principles for BC inverse design and showcases the exceptional capacity to integrate computational techniques to accelerate catalyst inverse design. 展开更多
关键词 Machine learning dft Biochar-based catalysts Nonradical activation PEROXYMONOSULFATE Inverse design META-ANALYSIS
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Synergistic machine learning and DFT screening strategy:Accelerating discovery of efficient perovskite passivators
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作者 Jianghao Liu Hongyan Lv +4 位作者 Pengyang Wang Guofu Hou Ying Zhao Xiaodan Zhang Qian Huang 《Journal of Energy Chemistry》 2026年第1期56-63,I0003,共9页
Efficient surface passivation is critical for achieving high-performance perovskite solar cells(PSCs),yet the discovery of optimal passivators remains a time-consuming,trial-and-error process.Here,we report a synergis... Efficient surface passivation is critical for achieving high-performance perovskite solar cells(PSCs),yet the discovery of optimal passivators remains a time-consuming,trial-and-error process.Here,we report a synergistic machine learning(ML)and density functional theory(DFT)approach that enables predictive and rapid identification of effective passivation materials.By training an XGBoost model(91.3%accuracy)with DFT-derived molecular descriptors and activity calculations,we identify 2-(4-aminophenyl)-3H-benzimidazol-5-amine(APBIA)as a promising passivator.Experimental validation demonstrates that APBIA effectively removes surface impurities and passivates defects within perovskite films,leading to a significant increase in power conversion efficiency(PCE)from 22.48%to 25.55%(certified as 25.02%).This ML-DFT framework provides a generalizable pathway for accelerating the development of advanced functional materials for photovoltaic applications. 展开更多
关键词 Perovskite solar cells Machine learning(ML) Density functional theory(dft) Passivators Organic molecule
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基于DFT的氢基竖炉内H_(2)和CO在Fe_(2)O_(3)(0001)表面反应的机理
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作者 唐珏 储满生 +1 位作者 刘西财 刘杰 《东北大学学报(自然科学版)》 北大核心 2025年第7期139-147,共9页
氢基竖炉工艺可显著减少CO_(2)排放,是钢铁工业绿色低碳发展的有效途径.本研究基于密度泛函理论(DFT),深入研究了氢基竖炉冶炼过程中H_(2)和CO与Fe_(2)O_(3)的反应机理.结果表明:H_(2)分子最稳定吸附构型的吸附能为-1.65 eV,CO分子为-2.... 氢基竖炉工艺可显著减少CO_(2)排放,是钢铁工业绿色低碳发展的有效途径.本研究基于密度泛函理论(DFT),深入研究了氢基竖炉冶炼过程中H_(2)和CO与Fe_(2)O_(3)的反应机理.结果表明:H_(2)分子最稳定吸附构型的吸附能为-1.65 eV,CO分子为-2.10 eV,CO分子吸附占优.H_(2)分子反应时的能垒为0.64 eV,CO分子为1.40 eV,H_(2)分子与Fe_(2)O_(3)反应在动力学上占优.升高温度虽然不利于气体分子的吸附,但有利于还原反应的进行,因此升高温度可以弥补H_(2)分子吸附及反应在热力学上的劣势.对于富氢或纯氢竖炉,可以提高操作压力,同时适当提高还原温度以加快反应速率,但应确保吸附效率. 展开更多
关键词 氢基竖炉 密度泛函理论(dft) Fe_(2)O_(3) 反应机理 吸附能 能垒
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层状双氢氧化物负载生物炭对磷的吸附机制及DFT
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作者 马锋锋 康宏兵 +4 位作者 赵浩 郑旭东 张建 李庆 焦雅仙 《环境科学》 北大核心 2025年第7期4360-4369,共10页
利用层状双氢氧化物(LDHs)负载马铃薯秸秆生物炭(SBC),制备了层状双氢氧化物负载马铃薯秸秆生物炭的复合材料(LDHs@SBC),研究了其对磷的吸附性能,并利用密度泛函理论(DFT)从分子层面分析了吸附机制.结果表明,LDHs@SBC对磷的吸附动力学... 利用层状双氢氧化物(LDHs)负载马铃薯秸秆生物炭(SBC),制备了层状双氢氧化物负载马铃薯秸秆生物炭的复合材料(LDHs@SBC),研究了其对磷的吸附性能,并利用密度泛函理论(DFT)从分子层面分析了吸附机制.结果表明,LDHs@SBC对磷的吸附动力学过程可被准二级动力学模型(R^(2)=0.983)很好地拟合,主要吸附过程为化学吸附.热力学分析表明,LDHs@SBC对磷的吸附过程为自发的放热反应.通过DFT计算显示,LDHs@SBC吸附磷的吸附能为−5.34 eV,进一步验证了其吸附过程为化学吸附以及自发的放热过程.吸附机制主要包括P-p/s、O-p和M-p/s轨道的杂化形成配位键P—O—M,产生较强的电子转移和轨道贡献.溶液pH值影响磷酸盐的赋存形态及LDHs@SBC的电荷分布,通过形成普通氢键(OHB)和电荷辅助氢键(CAHB)使LDHs@SBC对磷的吸附量达到最大.LDHs@SBC吸附磷的主要机制包括静电吸引、沉淀作用、配体交换以及电荷辅助氢键等.LDHs@SBC对磷具有较强的吸附性能且重复利用性好,是一种在含磷废水处理领域具有应用前景的高效、可再生的吸附材料. 展开更多
关键词 层状双氢氧化物(LDHs) 生物炭 吸附 密度泛函理论(dft)
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DFT and TD-DFT Study of Bis[2-(5-Amino-[1,3,4]-Oxadiazol-2-yl) Phenol](Diaqua)M(II) Complexes [M = Cu, Ni and Zn]: Electronic Structures, Properties and Analyses 被引量:2
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作者 Nyiang Kennet Nkungli Julius Numbonui Ghogomu +1 位作者 Ludovid Ngouo Nogheu Shridhar Ramachandra Gadre 《Computational Chemistry》 2015年第3期29-44,共16页
Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transitio... Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-to-metal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intraligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes. 展开更多
关键词 dft td-dft AOYP COMPLEXES NBO Analysis MEP Surfaces
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甲醇在Cu_(4)-C_(5)N_(2)H_(2)表面吸附和裂解机理的DFT研究 被引量:2
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作者 王婉楠 任瑞鹏 吕永康 《分子催化(中英文)》 北大核心 2025年第1期34-40,I0002,共8页
开发高效稳定的甲醇制甲醛催化剂意义重大,但催化剂稳定性差和甲醛选择性低的问题仍然存在.以嵌入氮化碳中的铜四原子团簇(Cu_(4)-C_(5)N_(2)H_(2))催化剂作为模型,基于DFT-D3探索了甲醇在催化剂表面吸附和裂解反应机理.结果表明,Cu_(4)... 开发高效稳定的甲醇制甲醛催化剂意义重大,但催化剂稳定性差和甲醛选择性低的问题仍然存在.以嵌入氮化碳中的铜四原子团簇(Cu_(4)-C_(5)N_(2)H_(2))催化剂作为模型,基于DFT-D3探索了甲醇在催化剂表面吸附和裂解反应机理.结果表明,Cu_(4)-C_(5)N_(2)H_(2)具有优异的稳定性和高的甲醛选择性,甲醇在Cu_(4)-C_(5)N_(2)H_(2)表面裂解的最优路径为CH_(3)OH→CH_(3)O→CH_(2)O,电荷分析结果显示催化剂与甲醇之间的电子转移使得甲醇得以活化.这些结果为合理设计高效甲醇制甲醛催化剂提供了理论指导. 展开更多
关键词 甲醇 甲醛 dft Cu_(4)-C_(5)N_(2)H_(2) 裂解机理
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TD-DFT Calculation on the UV-Vis Spectra of Complex 8-((Trimethoxysilyl)methylthio)quinoline·SnCl_4 被引量:2
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作者 曾义 陈新 薛英 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第5期547-552,共6页
Electronic structures and absorption spectra properties of complex 8-((trimethoxysilyl)methylthio)quinoline.SnCh in gas phase and MeCN media have been investigated by using DFT/TD-DFT method. The calculated lowest... Electronic structures and absorption spectra properties of complex 8-((trimethoxysilyl)methylthio)quinoline.SnCh in gas phase and MeCN media have been investigated by using DFT/TD-DFT method. The calculated lowest-energy absorption band shows different mechanisms under these two conditions, and it bears LMCT/LLCT/ILCT character in MeCN solution and LLCT/ILCT character in gas phase. The calculated absorption bands of the title complex in MeCN solvent are in good agreement with the experimental results, and calculation results indicate that the very weak experimentally observed lowest-energy absorption band of the title complex in MeCN solvent originates from the spin-forbidden singlet-triplet transitions. 展开更多
关键词 8-((trimethoxysilyl)methylthio)quinoline-SnCl4 td-dft solvent effect transitionmechanism
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TD-DFT Study on the Electronic Spectrum Properties of 2,7′-(Ethylene)-bis-8-hydroxyquinoline and Its Derivatives 被引量:1
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作者 李志锋 朱元成 +1 位作者 袁焜 康敬万 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2008年第1期63-69,共7页
The structures of 2,7'-(ethylene)-bis-8-hydroxyquinoline and its derivatives were optimized at the ground states using ab initio HF and B3LYP methods. At the same time, the molecular structures of the first singlet... The structures of 2,7'-(ethylene)-bis-8-hydroxyquinoline and its derivatives were optimized at the ground states using ab initio HF and B3LYP methods. At the same time, the molecular structures of the first singlet excited state for 2,7'-(ethylene)-bis-8-hydroxyqulnoline and its derivatives were optimized by CIS/6-31G(d). The absorption and emission spectra based on the above structures were obtained by the time-dependent density functional theory (TD-DFT) by the B3LYP method with the 6-31G(d) basis set. The calculated results of luminescence originate from the electronic transition from the hydroxphenol ring of 8-hydroxyquinoline A to the pyridine ring of 8-hydroxyquinoline B. Their luminescence wave bands can be tuned by different substituents on the ligand of 8-hydroxyquinoline. 展开更多
关键词 8-hydroxyquinolinolinato derivative electron spectrum excited state td-dft
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TD-DFT Study on Pyrazoline Derivatives 被引量:1
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作者 MIAO Ti-Fang ZHANG Jian-Fu LI Shuang 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第10期1169-1175,共7页
The molecular structures of ground state and first single excited state for pyrazoline derivatives are optimized with DFT B3LYP method and ab initio “configuration interaction with single excitations”(CIS) method,... The molecular structures of ground state and first single excited state for pyrazoline derivatives are optimized with DFT B3LYP method and ab initio “configuration interaction with single excitations”(CIS) method, respectively. The frontier molecular orbital characteristics have been analyzed systematically, and the electronic transition mechanism has been discussed. Electronic spectra are calculated by using TD-DFT method. These results are consistent with those from the experiment. 展开更多
关键词 pyrazoline derivatives electron transfer time-dependent density functional theory td-dft electronic spectrum
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基于改进CORDIC算法的DFT解调方法
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作者 焦宇涛 曹胜利 +1 位作者 岳钊 赵二刚 《南开大学学报(自然科学版)》 北大核心 2025年第3期59-65,共7页
调制解调法是一种常用的微弱信号检测方法,高精度、低复杂度的解调方法的实现对于调制解调法的应用具有重要的意义.传统坐标旋转数字计算(coordinate rotation digital computer,CORDIC)算法具有占用资源多,需要缩放因子补偿等问题.因... 调制解调法是一种常用的微弱信号检测方法,高精度、低复杂度的解调方法的实现对于调制解调法的应用具有重要的意义.传统坐标旋转数字计算(coordinate rotation digital computer,CORDIC)算法具有占用资源多,需要缩放因子补偿等问题.因此设计并实现了一种基于改进CORDIC算法的离散傅里叶变换(discrete Fourier transform,DFT)解调方法用于微弱信号的检测.首先改进了传统的CORDIC算法用于正余弦函数值的计算,该方法不仅免除了缩放因子,而且不需要进行旋转角度的判断,降低了算法的资源占用;然后基于该CORDIC算法设计了DFT解调算法,避免了乘法器与大量查找表的使用.最终仿真结果表明,设计的DFT解调方法在整周期采样的情况下能够实现对调制信号的高精度解调,并且具备良好的抗噪声性能,能够满足微弱信号检测的要求. 展开更多
关键词 dft解调 免缩放因子CORDIC 调制解调法 微弱信号检测
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FeMo双原子催化CO_(2)氧化C_(3)H_(8)反应机理的DFT研究
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作者 高鑫海 王婉楠 +2 位作者 石涛 任瑞鹏 吕永康 《分子催化(中英文)》 北大核心 2025年第3期208-215,I0001,I0002,共10页
CO_(2)氧化C_(3)H_(8)脱氢反应可有效抑制过度脱氢现象并提高丙烯产率,但如何设计高效催化剂是关键.本研究构建了Fe/Mo-C_(2)N和Fe/MoS-C_(2)N两种催化剂模型,并基于密度泛函理论探索了C_(3)H_(8)和CO_(2)在催化剂表面的反应机理.研究... CO_(2)氧化C_(3)H_(8)脱氢反应可有效抑制过度脱氢现象并提高丙烯产率,但如何设计高效催化剂是关键.本研究构建了Fe/Mo-C_(2)N和Fe/MoS-C_(2)N两种催化剂模型,并基于密度泛函理论探索了C_(3)H_(8)和CO_(2)在催化剂表面的反应机理.研究结果表明,所构建的催化剂可以实现FeMo双原子同步活化C_(3)H_(8)和CO_(2),C_(3)H_(8)+CO_(2)→CH_(3)CHCH_(3)+COOH→CH_(3)CHCH_(2)+CO+H_(2)O为最优路径.差分电荷分析结果显示,S掺杂促进了Mo原子向CO_(2)的电荷转移,从而提升催化活性.本研究可为设计CO_(2)氧化C_(3)H_(8)脱氢反应催化剂提供理论依据. 展开更多
关键词 双原子催化 FeMo dft C_(3)H_(8) CO_(2) C_(2)N
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