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Updated: Feb 24, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Published on: May 27, 2020

UTDA-xDH：無制限タム・ダンコフ近似におけるXYG3型二重混合密度汎関数による正確な二重励起エネルギー

Qinjie Yang¹, Xin Xu^1,2

¹Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM), Shanghai Key Laboratory of Molecular Catalysis and Innovation Materials, MOE Laboratory for Computational Physical Science, Research Center for Chemical Theory, Department of Chemistry, Fudan University, Shanghai 200438, China.

The journal of physical chemistry letters

|February 23, 2026

Abstract:

We develop UTDA-xDH, an excited-state method that combines the XYG3-type doubly hybrid density functional (xDH) with the unrestricted Tamm-Dancoff approximation (UTDA). Three xDH methods, XYG3, XYGJ-OS, and xDH-PBE0, are assessed against a data set of doublet-doublet excitation energies of small radicals. All three xDHs exhibit excellent accuracy and robustness for both valence and Rydberg excitations, with mean absolute deviations of 0.07-0.13 eV. These results not only outperform conventional density functional theory methods but also rival the unrestricted equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) method. Remarkably, the assessed xDHs show substantially reduced spin contamination compared to non-xDH counterparts, enabling highly accurate predictions even for challenging cases such as the ²Σ⁺ state of CNO. These results support (U)TDA-xDH as an efficient, broadly applicable excited-state approach for open- and closed-shell systems.

キーワード:

励起状態計算二重混合密度汎関数無制限タム・ダンコフ近似ラジカル精度

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