Topology-dependent refinement of molecular structures and vibrational properties
Luigi Crisci1, Federico Lazzari1, Lina Uribe1
1Scuola Superiore Meridionale, Largo San Marcellino 10, 80138 Napoli, Italy.
The Journal of Chemical Physics
|August 10, 2026
Summary
This study introduces a new method to correct errors in computational chemistry models for molecular structures and vibrations. The topology-dependent local refinement significantly improves accuracy for various molecules, especially in hydrogen-bonded systems.
Area of Science:
- Computational chemistry
- Quantum chemistry
- Molecular modeling
Background:
- High-resolution spectroscopy reveals limitations in current electronic-structure models for medium-sized molecules.
- Residual errors in density-functional theory (DFT) affect equilibrium structures, rotational constants, and vibrational frequencies.
- These errors are particularly significant at the scale probed by modern experimental techniques.
Purpose of the Study:
- To develop a novel topology-dependent local refinement scheme to correct residual errors in electronic-structure calculations.
- To improve the accuracy of predicted equilibrium structures, rotational constants, and vibrational frequencies.
- To provide a computationally economical route for enhanced accuracy within standard workflows.
Main Methods:
- A transferable core-valence layer is introduced, separable from the valence hierarchy.
- Level 1 refinements include bond field and pair-local corrections, generalizing valence corrections.
- Residuals are represented in compact, low-dimensional spaces (normal-mode or fragment space) selected by molecular topology.
- The correction layer is continuous along the potential-energy surface, anchoring residuals to local chemical environments.
Main Results:
- Rotational constant errors in rigid covalent molecules are reduced by over an order of magnitude (from ~1% to <0.1%).
- Discrepancies in hydrogen-bonded carbohydrates are lowered to below 0.3% using pair-local refinement.
- The method demonstrates effectiveness across diverse systems including polycyclic aromatic hydrocarbons, intramolecular hydrogen bonds, carbohydrates, and nucleosides.
- Transferable pair-local corrections are parameterized for specific systems like intramolecular OH⋯O interactions.
Conclusions:
- Residual structural and vibrational errors are not uniform but can be organized by molecular topology and observable.
- The developed local refinement scheme offers an economical and accurate approach to improve molecular structures and vibrational analyses.
- This method enhances the reliability of computational chemistry for systems where high precision is required.
Related Concept Videos
02:37VSEPR Theory
Valence shell electron-pair repulsion theory (VSEPR theory) enables us to predict the molecular structure around a central atom from an examination of the number of bonds and lone electron pairs in its Lewis structure. The VSEPR model assumes that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsions between these electron pairs by maximizing the distance between them. The electrons in the valence shell of a central atom form either bonding...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...
01:24IR Spectroscopy: Molecular Vibration Overview
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
02:16Resonance and Hybrid Structures
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.