Realistic foundations for improving the accuracy in refractometry based on an extension of the Lorentz–Lorenz relation

S. Moltó, M.A. Sáenz-Nuño, E. Bernabéu Martínez

Results in Optics Vol. 25, pp. 101180

Summary:

Reliable determination of virial coefficients is essential for accurate interpretation of molecular properties, chemical and optical measurements, but their contributions often introduce significant uncertainty when applying the Lorentz–Lorenz relation. In this work, we propose a complementary approach that incorporates molecular dimensions and shape descriptors into the analysis. By studying eight representative molecules, we evaluated their charge-density dimensions and degree of asphericity, from which a new parameter, the shape factor, was defined. This parameter quantifies deviations from ideal behavior and, when applied, reduces the effective influence of virial coefficients by nearly three orders of magnitude. The introduction of the shape factor thus provides a practical tool to minimize systematic errors, enhance measurement precision, and improve the reliability of property estimations derived from the Lorentz–Lorenz equation. Furthermore, this paper presents the validation of an algorithm that facilitates the calculation of refractometric measurements by including the shape factor and molecular species, offering a computational method to streamline data analysis and support experimental design.

Spanish layman's summary:

Los coeficientes viriales son fundamentales para estimar con precisión las propiedades moleculares, pero suelen introducir incertidumbre en la relación de Lorentz-Lorenz. Un nuevo factor de forma molecular reduce su impacto en tres órdenes de magnitud, mejorando la precisión y facilitando cálculos refractométricos más eficientes.

English layman's summary:

Reliable virial coefficients are key for accurate molecular property estimation but often add uncertainty in the Lorentz-Lorenz relation. A new molecular shape factor reduces their impact by three orders of magnitude, improving precision and enabling efficient refractometric calculations.

Keywords: Molecular asphericity; Molecular shape factor; Virial coefficient

JCR-JIF Impact Factor and WoS quartile: 3,300 - Q2 (2025)

DOI reference: https://doi.org/10.1016/j.rio.2026.101180

Published on paper: April 2026.

Published on-line: October 2026.

Citation:
S. Moltó, M.A. Sáenz-Nuño, E. Bernabéu Martínez, "Realistic foundations for improving the accuracy in refractometry based on an extension of the Lorentz–Lorenz relation", Results in Optics, Vol. 25, pp. 101180, April 2026. [Online: October 2026] doi: 10.1016/j.rio.2026.101180