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The Angular Localization Function (ALF): A Practical Tool to Measure Solvent Angular Order with Molecular Density
Maïwenn Souetre1, Benjamin Rotenberg1,2, Guillaume Jeanmairet1,2
1Sorbonne Université, CNRS, Physico-Chimie des Électrolytes et Nanosystèmes Interfaciaux, PHENIX, Paris F-75005, France.
The Journal of Physical Chemistry. B
|June 3, 2026
Summary
Researchers developed the Angular Localization Function (ALF) to analyze solvent structure. This new method quantifies local angular order, offering deeper insights into molecular interactions and solvent behavior.
Area of Science:
- Computational chemistry
- Physical chemistry
- Materials science
Background:
- Molecular density functional theory (DFT) computes solvent density around solutes.
- Interpreting the detailed solvent structure from DFT is challenging.
- Current analyses often neglect angular information of solvent molecules.
Purpose of the Study:
- Introduce a new function, the Angular Localization Function (ALF).
- Quantify local angular order and entropy of solvent molecules.
- Enhance the interpretation of molecular solvent structure.
Main Methods:
- Derived ALF from the ideal free energy functional.
- Analyzed solvent structure for water, octanol, and clay minerals (talc, fluorotalc, pyrophyllite) in water.
- Connected ALF to established statistical functions.
Main Results:
- ALF provides a local measure of angular order.
- Demonstrated ALF's utility in characterizing solvent orientation around solutes and surfaces.
- Showcased ALF's complementary information to polarization and charge density.
Conclusions:
- ALF offers a novel way to analyze solvent orientational distribution.
- ALF serves as a valuable visualization tool, similar to the Electronic Localization Function (ELF).
- The method reveals subtle effects of solute structure on water interactions.
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