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

Atomic Nuclei: Nuclear Relaxation Processes01:23

Atomic Nuclei: Nuclear Relaxation Processes

In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis,  the precessing magnetic moments are randomly oriented around the z-axis. This...
Atomic Nuclei: Nuclear Spin State Population Distribution01:14

Atomic Nuclei: Nuclear Spin State Population Distribution

Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
Atomic Nuclei: Nuclear Spin State Overview01:03

Atomic Nuclei: Nuclear Spin State Overview

NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

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 slanted or...
Spin–Spin Coupling Constant: Overview01:08

Spin–Spin Coupling Constant: Overview

In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

You might also read

Related Articles

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

Sort by
Same author

International Expert Consensus on the Diagnosis and Clinical Management of Primary Fetal Pleural Effusion.

Prenatal diagnosis·2026
Same author

Why projection-based WF-in-DFT cannot be exact, even with the exact exchange-correlation functional. Formal and practical sources of errors.

The Journal of chemical physics·2026
Same author

A Stochastic Cluster Expansion for Electronic Correlation in Large Systems.

The journal of physical chemistry letters·2026
Same author

Fetoscopic myelomeningocele repair: standard technique and approaches for closure of large defects.

Neurosurgical focus: Video·2026
Same author

Fetal Intervention for Giant Chorangioma with Prenatal Ductus Arteriosus Closure: A Case Report.

Fetal diagnosis and therapy·2026
Same author

Multispin Entangled Polyradical Roaming Reactions from Spin-Symmetry Breakings and Aromatic Ring Fission in Nitroaromatic Energetic Molecules.

JACS Au·2026

Related Experiment Video

Updated: Jul 15, 2026

Spatial Separation of Molecular Conformers and Clusters
10:37

Spatial Separation of Molecular Conformers and Clusters

Published on: January 9, 2014

Stochastic Cluster Expansion for Spin-Flip Excitations.

Annabelle Canestraight1, Russell Miller2, Libor Veis3

  • 1Department of Chemical Engineering, University of California, Santa Barbara, California 93106-9510, United States.

The Journal of Physical Chemistry Letters
|July 14, 2026
PubMed
Summary

This study introduces a new method for calculating excited-state electronic structures in complex systems. It accurately predicts excitation energies using a minimal chemical subspace and stochastic sampling, overcoming limitations of traditional approaches.

More Related Videos

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
09:00

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Published on: June 28, 2018

Related Experiment Videos

Last Updated: Jul 15, 2026

Spatial Separation of Molecular Conformers and Clusters
10:37

Spatial Separation of Molecular Conformers and Clusters

Published on: January 9, 2014

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
09:00

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Published on: June 28, 2018

Area of Science:

  • Quantum Chemistry
  • Computational Materials Science
  • Electronic Structure Theory

Background:

  • Calculating excited-state electronic structure in strongly correlated systems is computationally demanding.
  • Existing methods struggle with the exponential scaling of the many-body Hilbert space and active space construction.

Purpose of the Study:

  • To extend the stochastic cluster expansion (SCE) framework for ground-state energies to accurately calculate excitation gaps.
  • To develop a systematically improvable method for excited states in correlated systems.

Main Methods:

  • Formulating energy differences as a hierarchy of orbital-space cluster contributions.
  • Reconstructing excitation energies from reduced-rank calculations using a minimal frontier chemical subspace (FCS).
  • Employing stochastic sampling for the remaining orbital environment to reduce active space dependence.

Main Results:

  • Accurate singlet-triplet gaps were obtained for charge-transfer complexes and polyacenes.
  • Results agree well with full-system calculations, demonstrating the method's accuracy.
  • The method shows convergence with low-order cluster terms.

Conclusions:

  • The developed method provides a computationally efficient and accurate approach for excited-state calculations in correlated systems.
  • It significantly reduces the reliance on large or preselected active spaces.
  • This offers a systematically improvable framework for future studies of excited states.