Jove
Visualize
联系我们
JoVE
x logofacebook logolinkedin logoyoutube logo
关于 JoVE
概览领导团队博客JoVE 帮助中心
作者
出版流程编辑委员会范围与政策同行评审常见问题投稿
图书馆员
用户评价订阅访问资源图书馆顾问委员会常见问题
研究
JoVE JournalMethods CollectionsJoVE Encyclopedia of Experiments存档
教育
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab Manual教师资源中心教师网站
使用条款与条件
隐私政策
政策

相关概念视频

¹H NMR: Long-Range Coupling01:27

¹H NMR: Long-Range Coupling

2.0K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.0K
Double Resonance Techniques: Overview01:12

Double Resonance Techniques: Overview

303
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
303
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

1.1K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.1K
Free Energy Changes for Nonstandard States03:25

Free Energy Changes for Nonstandard States

11.7K
The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:
 
where R is the gas constant (8.314 J/K·mol), T is the absolute temperature in kelvin, and Q is the reaction quotient. This equation may be used to predict the spontaneity of a process under any given set of conditions.
Reaction Quotient...
11.7K
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

1.6K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
1.6K
Atomic Spectroscopy: Absorption, Emission, and Fluorescence01:23

Atomic Spectroscopy: Absorption, Emission, and Fluorescence

1.3K
Atomic spectroscopy is a vital tool in elemental analysis, both qualitatively and quantitatively. It can be broadly divided into optical spectroscopy, mass spectroscopy, and X-ray spectroscopy methods. The optical spectroscopic methods are atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES), and atomic fluorescence spectroscopy (AFS). The first step in all three methods is atomization, where the solid, liquid, or solution-phase samples are converted into gas-phase atoms and...
1.3K

您也可能阅读

相关文章

通过共同作者、期刊和引用图与本文相关的文章。

排序
Same author

Introducing PAIMP, the polarizable ab initio model potential method for embedded clusters.

The Journal of chemical physics·2026
Same author

Reduced Density Matrix and Cumulant Approximations of Quantum Linear Response.

Journal of chemical theory and computation·2026
Same author

The photohydrolysis of furans.

Science (New York, N.Y.)·2026
Same author

Exact closed-form expressions for unitary spin-adapted fermionic singlet double excitation operators.

The Journal of chemical physics·2025
Same author

Redundant parameter dependencies in conventional and quantum linear response and equation of motion theory for unitary parameterized wave functions.

The Journal of chemical physics·2025
Same author

Time-Dependent Multiconfigurational Short-Range Density Functional Theory with Generalized Valence Bond Wave Functions.

The journal of physical chemistry. A·2025
Same journal

Stability constants of lanthanide-nitrate complexes in aqueous solutions: a theoretical study.

Physical chemistry chemical physics : PCCP·2026
Same journal

Lead-free Cs<sub>3</sub>MnCl<sub>5</sub> and CsMnCl<sub>3</sub> crystals: rapid on-chip crystallization, phase transition and fluorescence sensing applications.

Physical chemistry chemical physics : PCCP·2026
Same journal

F-Interstitial passivation preserves host-like optoelectronic properties in <sup>229</sup>Th:YLF nuclear-clock platforms.

Physical chemistry chemical physics : PCCP·2026
Same journal

Structural trends of tryptophan dimer: hydrogen bonding <i>versus</i> π-stacking from an energy decomposition analysis perspective.

Physical chemistry chemical physics : PCCP·2026
Same journal

Achieving high thermoelectric performance in Sb<sub>2</sub>Se<sub>3</sub>-alloyed GeTe through synergistic optimization of electrical and thermal transport.

Physical chemistry chemical physics : PCCP·2026
Same journal

Ultraviolet perfect absorption leveraging bound states in the continuum in an Al/SiO<sub>2</sub> hybrid system.

Physical chemistry chemical physics : PCCP·2026
查看所有相关文章

相关实验视频

Updated: Sep 16, 2025

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
08:04

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

8.5K

基于状态平均长距离CASSCF短距离DFT的激发状态方法.

Benjamin Helmich-Paris1, Erik Rosendahl Kjellgren2, Hans Jørgen Aa Jensen2

  • 1Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany. helmichparis@kofo.mpg.de.

Physical chemistry chemical physics : PCCP
|July 10, 2025
PubMed
概括
此摘要是机器生成的。

两个新的方法,SA-CAS-srDFT和CI-srDFT,使用密度函数理论计算激发状态. CI-srDFT显示有机分子的精度提高,为电子刺激能量计算提供了更可靠的方法.

更多相关视频

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
12:11

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

8.3K
Analysis of SEC-SAXS data via EFA deconvolution and Scatter
10:59

Analysis of SEC-SAXS data via EFA deconvolution and Scatter

Published on: January 28, 2021

9.2K

相关实验视频

Last Updated: Sep 16, 2025

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
08:04

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

8.5K
Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
12:11

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

8.3K
Analysis of SEC-SAXS data via EFA deconvolution and Scatter
10:59

Analysis of SEC-SAXS data via EFA deconvolution and Scatter

Published on: January 28, 2021

9.2K

科学领域:

  • 计算化学计算化学
  • 量子化学 是一个量子化学.
  • 理论化学 理论化学

背景情况:

  • 精确计算激发状态对于理解分子性质和反应至关重要.
  • 像CASSCF-DFT这样的现有方法在准确性和适用性方面存在局限性,特别是在复杂的系统中.

研究的目的:

  • 开发和评估基于状态平均 (SA) 的新方法来计算激发状态.
  • 将这些新方法的性能与各种分子系统的现有方法进行比较.

主要方法:

  • 提出了两个不同的基于状态平均 (SA) 的方法:SA-CAS-srDFT和CI-srDFT.
  • 使用了长距离完全活跃空间自我一致场 (CASSCF) 短距离密度函数理论 (DFT) 方法 (CAS-srDFT).
  • 采用总一体和顶部对密度 (OTPD) 来进行最终能量评估,并与多重配置对密度函数理论 (MC-PDFT) 进行基准测试.

主要成果:

  • 与SA-CAS-srDFT不同,CI-srDFT为乙烯提供了物理正确的潜在曲线.
  • CI-srDFT显示激发能量的依赖性减少了对平均状态数量的依赖性.
  • 使用sr-ctPBE功能,CI-srDFT在有机染色体的单点激发能达到0.17 eV的平均绝对误差.
  • 开发的方法对有机分子显示了令人印象深刻的准确性,但不能转移到过渡金属复合体.

结论:

  • 与SA-CAS-srDFT相比,CI-srDFT是计算有机分子激发状态的更准确,更可靠的方法.
  • 当前的CASSCF-DFT和MC-PDFT方法对CASSCF激发能没有持续的改进,特别是对于过渡金属复合体.