On the performance of QTP functionals applied to second-order response properties II: Dynamic polarizability and long-range C$_6$ coefficients

TL;DR

This study evaluates the performance of various QTP functionals in predicting frequency-dependent properties like dynamic polarizabilities and C$_6$ coefficients, comparing them with high-level methods and identifying the most accurate functionals.

Contribution

It extends previous work by analyzing the accuracy of QTP functionals for dynamic properties and dispersion coefficients across multiple wavelengths.

Findings

QTP functionals TPSS0 and QTP01 excel in dynamic polarizability predictions.

O3LYP provides the best overall performance for C$_6$ dispersion coefficients.

QTP01 and LC-QTP are most accurate within the QTP family for C$_6$ coefficients.

Abstract

This work is the second in the series "On the performance of QTP functionals applied to second-order response properties." In the first paper (J. Chem. Phys. 162, 054105, 2025), we demonstrated the good performance of Quantum Theory Project functionals in predicting static perturbed second-order properties, such as static polarizabilities, nuclear magnetic resonance (NMR) spin-spin coupling constants, and NMR chemical shifts. In the present study, we focus on frequency-dependent properties, namely dynamic polarizabilities and C$_6$ dispersion coefficients. For completeness, a total of 25 exchange-correlation (XC) functionals were investigated. Dynamic polarizabilities were evaluated at five different perturbation wavelengths: 632.99 nm, 594.10 nm, 543.52 nm, 514.50 nm, and 325.13 nm. This property was also computed using HF and EOM-CCSD. In general, EOM-CCSD results are very close to those obtained with linear-response CC3, except at the highest frequency. Among Kohn-Sham calculations, TPSS0 and QTP01 showed the best overall performance for dynamic polarizabilities. We also assessed how well QTP functionals reproduce the pole structure of the CO molecule. For the C$_6$ dispersion coefficients, calculations were performed using the Casimir-Polder equation. The best overall performance was obtained with O3LYP; however, the first eleven ranked functionals show very similar accuracy. Within the QTP family, QTP01 and LC-QTP provide the best results for C$_6$ coefficients.