Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

2D NMR: Overview of Heteronuclear Correlation Techniques01:18

2D NMR: Overview of Heteronuclear Correlation Techniques

906
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other...
906
Chemical Shift: Internal References and Solvent Effects01:17

Chemical Shift: Internal References and Solvent Effects

1.6K
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
1.6K
2D NMR: Overview of Homonuclear Correlation Techniques01:16

2D NMR: Overview of Homonuclear Correlation Techniques

798
Homonuclear correlation spectroscopy (COSY) is a powerful technique used in Nuclear Magnetic Resonance (NMR) spectroscopy to study the correlations between nuclei of the same type within a molecule. It provides information about scalar couplings between adjacent nuclei, which helps determine connectivity and structural information. There are several COSY variants, each with its unique strengths and experimental parameters.
COSY90 is the standard two-dimensional (2D) COSY experiment that...
798
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)01:19

2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)

1.6K
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
1.6K
Valence Bond Theory and Hybridized Orbitals02:38

Valence Bond Theory and Hybridized Orbitals

33.0K
According to valence bond theory, a covalent bond results when: (1) an orbital on one atom overlaps an orbital on a second atom, and (2) the single electrons in each orbital combine to form an electron pair. The strength of a covalent bond depends on the extent of overlap of the orbitals involved. Maximum overlap is possible when the orbitals overlap on a direct line between the two nuclei.
A σ bond (single bond in a Lewis structure) is a covalent bond in which the electron density is...
33.0K
¹H NMR: Long-Range Coupling01:27

¹H NMR: Long-Range Coupling

2.9K
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...
2.9K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Structural dynamics around a hydrogen bond: Investigating the effect of hydrogen bond strengths on the excited state dynamics of carboxylic acid dimers.

The Journal of chemical physics·2024
Same author

The Challenges of Characterizing the Zooplankton Community Response Following Simulated Spills of Diluted Bitumen into Boreal Lake Limnocorrals.

Bulletin of environmental contamination and toxicology·2023
Same author

Machine Learning Configuration Interaction.

Journal of chemical theory and computation·2018
Same author

Millions of Boreal Shield Lakes can be used to Probe Archaean Ocean Biogeochemistry.

Scientific reports·2017
Same author

Torsional Motion of the Chromophore Catechol following the Absorption of Ultraviolet Light.

Physical review letters·2015
Same author

Approaching exact hyperpolarizabilities via sum-over-states Monte Carlo configuration interaction.

The Journal of chemical physics·2014

Related Experiment Video

Updated: Mar 30, 2026

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

8.8K

Investigating Multireference Character and Correlation in Quantum Chemistry.

J P Coe1, M J Paterson1

  • 1Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh, EH14 4AS, United Kingdom.

Journal of Chemical Theory and Computation
|November 18, 2015
PubMed
Summary
This summary is machine-generated.

This study evaluates multireference diagnostics in quantum chemistry, revealing how electron correlation and spatial entanglement are quantified. Findings show diagnostics accurately predict multireference character across diverse chemical systems.

More Related Videos

Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions
11:22

Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions

Published on: January 30, 2018

10.7K
Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
05:51

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

Published on: July 19, 2019

6.8K

Related Experiment Videos

Last Updated: Mar 30, 2026

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

8.8K
Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions
11:22

Using Three-color Single-molecule FRET to Study the Correlation of Protein Interactions

Published on: January 30, 2018

10.7K
Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
05:51

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

Published on: July 19, 2019

6.8K

Area of Science:

  • Quantum Chemistry
  • Computational Chemistry

Background:

  • Multireference character is crucial for accurately describing electronic structure in molecules.
  • Existing diagnostics for multireference character vary in their sensitivity to molecular orbital choices and correlation effects.

Purpose of the Study:

  • To review and analyze various multireference diagnostics in quantum chemistry.
  • To investigate the impact of molecular orbital choices on these diagnostics.
  • To assess the performance of diagnostics for systems with varying multireference and correlation characteristics.

Main Methods:

  • Review of established multireference diagnostics.
  • Analysis of P.-O. Löwdin's approach in terms of spatial entanglement.
  • Testing diagnostics on three example systems with different correlation and multireference properties.
  • Investigation using Monte Carlo configuration interaction calculations and natural orbitals.
  • Evaluation of coupled-cluster singles and doubles and density-functional theory diagnostics.

Main Results:

  • A multireference measure (MR) is robust to cutoff variations in Monte Carlo configuration interaction.
  • Natural orbitals influence the assessment of multireference character.
  • Coupled-cluster and density-functional theory diagnostics generally predict multireference character correctly for the studied systems.
  • Basis size affects the multireference character of stretched molecules.

Conclusions:

  • Multireference diagnostics provide valuable insights into electron correlation and entanglement.
  • The choice of molecular orbitals can influence diagnostic outcomes.
  • Standard computational methods offer reliable predictions of multireference character for many systems.