Related Experiment Video
Updated: Aug 30, 2025

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Computation of NMR shieldings at the CASSCF level using gauge-including atomic orbitals and Cholesky decomposition
Tommaso Nottoli1, Sophia Burger2, Stella Stopkowicz2
1Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, I-56124 Pisa, Italy.
Abstract:
We present an implementation of coupled-perturbed complete active space self-consistent field (CP-CASSCF) theory for the computation of nuclear magnetic resonance chemical shifts using gauge-including atomic orbitals and Cholesky decomposed two-electron integrals. The CP-CASSCF equations are solved using a direct algorithm where the magnetic Hessian matrix-vector product is expressed in terms of one-index transformed quantities. Numerical tests on systems with up to about 1300 basis functions provide information regarding both the computational efficiency and limitations of our implementation.
Related Concept Videos
Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Atomic Radii and Effective Nuclear Charge
NMR and Mass Spectroscopy of Carboxylic Acids
While α protons of carboxylic acids absorb at 2–2.5 ppm, β protons absorb further upfield.
Carboxylic acids are easily identified by dissolving them in deuterium oxide, which results in a rapid exchange of the acidic protons with deuterium. This leads to the...
¹H NMR: Interpreting Distorted and Overlapping Signals
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...
Nuclear Overhauser Enhancement (NOE)

