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Updated: Jun 2, 2026

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics

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Spin-adapted open-shell time-dependent density functional theory. II. Theory and pilot application.

Zhendong Li¹, Wenjian Liu, Yong Zhang

¹Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, People's Republic of China.

The Journal of Chemical Physics

|April 12, 2011

Summary

Spin-adapted time-dependent density functional theory (S-TD-DFT) accurately describes excited states in open-shell systems. This new method overcomes spin contamination issues found in unrestricted (U-TD-DFT) and restricted (R-TD-DFT) approaches.

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Published on: January 25, 2020

Area of Science:

Quantum Chemistry
Computational Chemistry
Theoretical Chemistry

Background:

Unrestricted Kohn-Sham-based time-dependent density functional theory (U-TD-DFT) often yields spin-contaminated excited states for open-shell systems.
Restricted open-shell Kohn-Sham-based TD-DFT (R-TD-DFT) is limited to singlet-coupled single excitations.

Purpose of the Study:

To introduce and evaluate the spin-adapted time-dependent density functional theory (S-TD-DFT) for calculating excited states of open-shell systems.
To compare the performance of S-TD-DFT against U-TD-DFT and R-TD-DFT.

Main Methods:

Implementation and application of S-TD-DFT.
Comparison with U-TD-DFT and R-TD-DFT for spin-conserving and spin-flip excitations.
Calculations performed on nitrogen (N2+) and naphthalene (C10H8+) cations.

Main Results:

S-TD-DFT successfully captures both singlet- and triplet-coupled single excitations.
S-TD-DFT provides a balanced description of excited states for open-shell systems.
U-TD-DFT results were found to be heavily spin-contaminated.

Conclusions:

S-TD-DFT offers a significant improvement over existing TD-DFT methods for open-shell systems.
The new method provides accurate and reliable excited-state properties.
S-TD-DFT achieves this with comparable computational cost to U-TD-DFT.