Themed collection Benchmark Experiments for Numerical Quantum Chemistry

This themed collection addresses the question of numerical quantum chemistry benchmarking in its many facets, with a focus on experiment-driven practices.

Experimental data provide reliable benchmarks for computed spin-state energetics.

The methodological advances made in recent years have significantly extended the range and dimensionality of noncovalently bound molecular complexes for which full-dimensional quantum calculations of their rovibrational states are feasible.

The first theory blind challenge addressing the effect of microsolvation on water vibrations is launched.

Rotational constants and equilibrium structures are strongly connected. To meet the 0.1% accuracy in the computation of the former, an accuracy of 0.0005–0.001 Å is required for bond lengths.

In this article, we review recent first principles, anharmonic studies on the molecular vibrations of gaseous formic acid in its monomer form.

Reactivity scales are powerful research tools. This tutorial shows how to create and use them on the computer.

Since the errors of quantum chemical methods can strongly vary across chemical space, the transferability of traditional benchmarks is limited. This can be overcome by quantifying the uncertainty of quantum chemical results in a system-focused way.

A joint community effort to critically evaluate quantum chemical approaches to the prediction of vibrational shifts of hydrates in the gas phase.

Benchmarking state-of-the-art computations of D₀(CH) with Active Thermochemical Tables reveals a systematic error in prior high-level computations.

The X–H bonds obtained from Hirshfeld atom refinements elongate with Hartree–Fock exchange in contrast to geometry optimizations. These results suggest new venues in benchmarking density functionals with respect to experimental crystallographic data.

Despite OH stretch excitation, the hydrogen atom between two TEMPO radicals does not tunnel fast enough to show up as a splitting in the supersonic jet infrared spectrum.

1D-hindered rotor profiles are corrected for coupled cluster energies at stationary points. Probability density functions at each energy level allow to resolve different conformations within the scan.

In contrast to standard DFT predictions, 2-naphthol is shown to dock on the oxygen of anisole, with excitation-dependent angular geometry.

High-resolution spectroscopy techniques play a pivotal role to validate and benchmark methods from quantum chemistry. This is crucial for small esters which exhibit a soft-degree of freedom around the C–C bond in proximity to the carbonyl moiety.

Benchmarking experiments and calculations using the “Lego brick” approach on cyanoethynylbenzene isomers.

We studied the accuracy of projection-based WFT-in-DFT embedding and LCCSD(T0):LMP2 embedding for predicting reaction energies and barriers of typical, closed-shell transition-metal-based reactions.

Targeted scoring function for different levels of biological hierarchy of selected GPCRs, leads to improvement in molecular docking predictive power.

Rotational spectroscopy relies on quantum chemical calculations to interpret hyperfine splitting.

The change in the cavity size of valinomycin in response to the size of the metal ion is revealed by cryogenic ion trap infrared spectroscopy.

Large ³¹P-NMR enhancements are observed with DNP in PPh₃ doped with BDPA radical, while they are reduced when a nitroxide radical or triphenylphosphine-oxide are used instead. This is due to different non-covalent radical/target molecule interactions.

A simple asymmetric ketone directs solvent molecules to the shorter end and this subtle preference is useful for theory benchmarking.

The time required for recording survey scans of the microwave spectrum of the title molecule with two inequivalent methyl internal rotors was significantly reduced with the help of adequate spectral analysis skill and quantum chemical benchmarking.

Stabilization of normally unstable enol form of carbonyl compounds on surfaces is realized via intermolecular interactions.

A high-dimensional neural network potential has been developed to study the harmonic and anharmonic frequencies of the formic acid dimer with coupled cluster accuracy.

We show that ring polymer molecular dynamics is able to include nuclear quantum effects in unimolecular dissociation simulations. In this way, rate constants directly take into account both quantum statistics and anharmonic behavior.

Application of group polarizability database towards better prediction of electric moments and electrostatic properties of biomolecules.

We introduce a set of 13 supramolecular complexes featuring diverse non-covalent interactions with heavy main group elements (Zn, As, Se, Te, Br, I), high charges (−2 up to +4), and large systems with up to 266 atoms (HS13L).

A four-dimensional-potential energy surface (4D-PES) of the atmospherically relevant CO₂–O₂ van der Waals complex is generated using ab initio methodology. Induced complexation shifts and second virial coefficient are also presented.

Quantum chemistry and rotational spectroscopy work hand-in-hand in the characterization of a potential chiral tag.

The absolute configuration of a molecule can be established by analysis of molecular rotational spectra of the analyte complexed with a small chiral molecule of known configuration.

Our novel correction procedure yields high-accuracy DFT predictions of absolute NMR shieldings and enables outliers due to relativistic effects or manifestly inadequate modelling of electron correlation to be easily and unambiguously identified.

Five conformers of the flexible molecule alpha-methoxy phenylacetic acid were identified using rotational spectroscopy. The conformational landscape, internal dynamics, and intramolecular interactions were investigated.

Raman and FTIR spectra of an acid–alcohol complex show complementary signatures from acidic and alcoholic OH stretching, proving its existence.

The interactions of limonene with the water dimer have been characterised through the identification of seven different isomers.

In this work we present nablaDFT, the new dataset and benchmark for the Density Functional Theory Hamiltonian and energy prediction. We provide data for over 1 million different molecules and over 5 million conformations and baseline models for both tasks.

The reaction of dichlorocarbene and molecular oxygen in their respective ground states is hindered by a considerable barrier rendering a diffusion controlled formation of the resulting Criegee intermediate unlikely.

Anion photoelectron spectroscopy has been used to determine the electron binding energies of the X⁻⋯C₃H₆ (X = Cl, Br, I) complexes.

The UV photodissociation of cryogenic-cooled isomer-selected cytosine–silver complex leads to the production of cytosine radical cation without isomerization.

The influence of long-range interactions on the structure of complexes of Eu(III) with four 9-hydroxy-phenalen-1-one ligands (HPLN) and one alkaline earth metal dication [Eu(PLN)₄AE]⁺ (AE: Mg, Ca, Sr, and Ba) is analyzed.

We demonstrate that X-ray scattering can be used as a probe of electron–electron correlation.

The protonated dimer of cyclo (Phe-His) is studied in a ion trap by IR spectroscopy. A β-sheet interaction exists in cyclo (LPhe-LHis) and not in cyclo (LPhe-DHis). A change in chirality of one of the residues thus prevents amyloid-type clustering.

A DLPNO-CCSD(T)-based protocol allows the accurate calculation of phosphorescence energies for aromatic compounds. The figure shows the computed and experimental spectra for a carbazolyl dicyanobenzene photocatalyst.

We benchmark GFB-xTB for periodic geometry optimisations of CoRE-MOF structures and find both local and global geometry well conserved.