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Evaluating the Performance of the Exact Integral Simplified Time-Dependent Density Functional Theory (XsTD-DFT) to
Marilù G Maraldi1, Marc de Wergifosse1
1Theoretical Chemistry Group, Molecular Chemistry, Materials and Catalysis Division (MOST), Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Place Louis Pasteur 1, Louvain-la-Neuve B-1348, Belgium.
The new exact integral simplified time-dependent density functional theory (XsTD-DFT) method significantly speeds up calculations for one-photon absorption (1PA) and two-photon absorption (2PA) in large molecules. This reliable and robust approach is ideal for quantum mechanical workflows.
Area of Science:
- Computational Chemistry
- Quantum Mechanics
- Spectroscopy
Background:
- Calculating one-photon absorption (1PA) and two-photon absorption (2PA) for large molecular systems using all-atom quantum mechanical (AQM) methods is computationally demanding.
- Existing methods face significant challenges in balancing accuracy with computational efficiency for these complex systems.
Purpose of the Study:
- To evaluate the performance of the novel exact integral simplified time-dependent density functional theory (XsTD-DFT) method for computing 1PA and 2PA.
- To assess the reliability, robustness, and computational efficiency of XsTD-DFT as a component in AQM workflows for realistic molecular systems.
Main Methods:
- The study employed the XsTD-DFT method, a simplified quantum chemistry (sQC) approach, for calculating 1PA and 2PA.
- Performance was benchmarked against rigorous RI-CC2 calculations and standard TD-DFT results.
- A diverse set of 91 organic molecules, including QUEST database systems, push-pull molecules, and microhydrated clusters, were analyzed.
Main Results:
- XsTD-DFT achieved a computational speed-up of up to three orders of magnitude compared to TD-DFT, particularly with an energy threshold of 9 eV.
- The method demonstrated robustness by accurately reproducing TD-DFT trends for excitation energies, oscillator strengths, and 2PA strengths.
- XsTD-DFT showed reliability in predicting structure-property relationships, handling non-equilibrium geometries, and modeling microhydrated systems, with experimental agreement comparable to TD-DFT.
Conclusions:
- XsTD-DFT is a reliable, robust, and computationally efficient method for calculating 1PA and 2PA.
- Its performance makes it a suitable key ingredient for AQM workflows, enabling the study of complex, realistic molecular systems.
- Guidelines for implementing XsTD-DFT in 1PA and 2PA calculations are provided.
