Excitation Spectra of Nucleobases with Multiconfigurational Density Functional Theory
| Autor: | Hans Jørgen Aa. Jensen, Erik D. Hedegård, Mickaël Hubert |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Quantitative Biology::Biomolecules
010304 chemical physics Electronic correlation Nucleotides Chemistry 010402 general chemistry 01 natural sciences 0104 chemical sciences Thymine chemistry.chemical_compound Coupled cluster Models Chemical Excited state 0103 physical sciences Density functional theory Complete active space Physical and Theoretical Chemistry Atomic physics Wave function Excitation |
| Zdroj: | Hubert, M, Jensen, H J A & Hedegård, E D 2016, ' Excitation Spectra of Nucleobases with Multiconfigurational Density Functional Theory ', The Journal of Physical Chemistry Part A, vol. 120, no. 1, pp. 36-43 . https://doi.org/10.1021/acs.jpca.5b09662 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/acs.jpca.5b09662 |
| Popis: | We present here the coupling of a polarizable embedding (PE) model to the recently developed multiconfiguration short-range density functional theory method (MC-srDFT), which can treat multiconfigurational systems with a simultaneous account for dynamical and static correlation effects. PE-MC-srDFT is designed to combine efficient treatment of complicated electronic structures with inclusion of effects from the surrounding environment. The environmental effects encompass classical electrostatic interactions as well as polarization of both the quantum region and the environment. Using response theory, molecular properties such as excitation energies and oscillator strengths can be obtained. The PE-MC-srDFT method and the additional terms required for linear response have been implemented in a development version of Dalton. To benchmark the PE-MC-srDFT approach against the literature data, we have investigated the low-lying electronic excitations of acetone and uracil, both immersed in water solution. The PE-MC-srDFT results are consistent and accurate, both in terms of the calculated solvent shift and, unlike regular PE-MCSCF, also with respect to the individual absolute excitation energies. To demonstrate the capabilities of PE-MC-srDFT, we also investigated the retinylidene Schiff base chromophore embedded in the channelrhodopsin protein. While using a much more compact reference wave function in terms of active space, our PE-MC-srDFT approach yields excitation energies comparable in quality to CASSCF/CASPT2 benchmarks. Range-separated hybrid methods between wave function theory and density functional theory (DFT) can provide high-accuracy results, while correcting some of the inherent flaws of both the underlying wave function theory and DFT. We here assess the accuracy for excitation energies of the nucleobases thymine, uracil, cytosine, and adenine, using a hybrid between complete active space self-consistent field (CASSCF) and DFT methods. The method is based on range separation, thereby avoiding all double-counting of electron correlation and is denoted long-range CASSCF short-range DFT (CAS-srDFT). Using a linear response extension of CAS-srDFT, we compare the first 7-8 excited states of the nucleobases with perturbative multireference approaches as well as coupled cluster based methods. Our results show that the CAS-srDFT method can provide accurate excitation energies in good correspondence with the computationally more expensive methods. |
| Databáze: | OpenAIRE |
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