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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Calculation of frequency-dependent hyperpolarizabilities using general coupled-cluster models.
Darragh P O'Neill1, Mihály Kállay, Jürgen Gauss
1Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany. oneill@uni-mainz.de
The Journal of Chemical Physics
|October 9, 2007
Summary
Calculating frequency-dependent hyperpolarizabilities is crucial. Our new coupled-cluster scheme, including triple excitations, provides essential accuracy for these molecular properties.
Area of Science:
- Quantum chemistry
- Computational physics
Background:
- Response theory and analytic derivative theory are key computational chemistry methods.
- Accurate calculation of molecular properties, such as hyperpolarizabilities, is vital for understanding material behavior.
Purpose of the Study:
- To develop a computational scheme for calculating frequency-dependent hyperpolarizabilities.
- To implement this scheme within the coupled-cluster (CC) framework, extending to high levels of theory.
Main Methods:
- Developed a method combining response theory and analytic derivative theory.
- Implemented the scheme for arbitrary coupled-cluster levels, up to full-configuration-interaction (FCI).
- Calculated frequency-dependent hyperpolarizabilities for small molecules.
Main Results:
- The new scheme enables accurate calculation of frequency-dependent hyperpolarizabilities.
- Inclusion of triple excitations in coupled-cluster calculations is essential for accurate results.
- The method is applicable to various levels of coupled-cluster theory.
Conclusions:
- The developed scheme provides an accurate and versatile tool for computing molecular hyperpolarizabilities.
- Triple excitations are critical for quantitatively describing these nonlinear optical properties.
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