Evaluation of exchange-correlation functionals for time-dependent density functional theory calculations on metal...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Accurate simulation of electronic absorption spectra is crucial for understanding metal complexes.
• Time-dependent density functional theory (TD-DFT) is a powerful computational tool for studying excited states.

Purpose of the Study:

• To evaluate the performance of various exchange-correlation (XC) functionals within TD-DFT for simulating copper and zinc complex spectra.
• To identify the most accurate XC functionals for predicting experimental electronic absorption spectra.

Main Methods:

• Simulated electronic absorption spectra of copper and zinc complexes using TD-DFT calculations.
• Compared 41 XC functionals, including pure and hybrid DFT methods.
• Optimized calculated spectra against experimental data using a Matlab script and assessed performance via RMSE, Q(F), and epsilon(SF) parameters.

Main Results:

• Hybrid DFT methods significantly outperformed pure DFT functionals.
• B1LYP, B97-2, B97-1, X3LYP, and B98 functionals demonstrated the highest accuracy.
• B1LYP provided the most accurate results for copper complexes (RMSE < 3.5%, Q(F) < 3.5%, epsilon(SF) > 0.990).
• For zinc complexes, PBE1PBE, mPW1PW91, and B1LYP showed good accuracy (RMSE/Q(F) 5.3-7.3%, epsilon(SF) ~0.930).

Conclusions:

• Modern TD-DFT calculations are highly effective for exploring excited state transitions in metal complexes.
• Hybrid XC functionals offer superior accuracy for spectral simulations compared to pure functionals.
• The choice of XC functional is critical for achieving reliable predictions of electronic absorption spectra.