Combining multilevel Hartree–Fock and multilevel coupled cluster approaches with molecular mechanics: a study of electronic excitations in solutions

Goletto, Linda; Giovannini, Tommaso; Folkestad, Sarai Dery; Koch, Henrik

doi:10.1039/d0cp06359b

Cited by 17 publications

(32 citation statements)

References 127 publications

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“…Yet, very encouraging results on the treatment of larger systems, including solvated systems, with CC accuracy come from the latest advances in multilevel coupled cluster theory. 62–65…”

Section: Discussionmentioning

confidence: 99%

Excited state absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Fedotov

Paul

Koch

et al. 2022

Phys. Chem. Chem. Phys.

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“…Yet, very encouraging results on the treatment of larger systems, including solvated systems, with CC accuracy come from the latest advances in multilevel coupled cluster theory. 62–65…”

Section: Discussionmentioning

confidence: 99%

Excited state absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Fedotov

Paul

Koch

et al. 2022

Phys. Chem. Chem. Phys.

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“…Yet, very encouraging results on the treatment of larger systems, including solvated systems, with CC accuracy come from the latest advances in multilevel coupled cluster theory. [60][61][62][63] Another interesting feature of TD-CAM-B3LYP is the relatively small dependence of the computed spectra on the size of the basis set. As shown in the SI, the spectra obtained at the TD-CAM-B3LYP/6-31G(d) level are fairly similar to the ones reported here, but for a moderate, almost uniform, blue-shift.…”

Section: Discussionmentioning

confidence: 99%

Transient Absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Fedotov

Paul

Koch

et al. 2021

Preprint

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We study the excited state absorption (ESA) properties of the four DNA bases (thymine, cytosine, adenine, and guanine) by different single reference quantum mechanical methods, i.e. equation of motion coupled cluster singles and doubles (EOM-CCSD), singles, doubles and perturbative triples (EOM-CC3), and time-dependent density functional theory (TD-DFT), with the long-range corrected CAM-B3LYP functional. Preliminary results at the Tamm-Dancoff (TDA) CAM-B3LYP level using the maximum overlap method (MOM) are reported for Thymine. In the gas phase, the three methods predict similar One Photon Absorption (OPA) spectra, which are also consistent with the experimental results and with the most accurate computational studies available in the literature. The ESA spectra are then computed for the pp states (one for pyrimidine, two for purines) associated with the lowest energy absorption band, and for the close-lying np state. The EOM-CC3, EOM-CCSD and CAM-B3LYP methods provide similar ESA spectral patterns, which are also in qualitative agreement with literature RASPT2 results. Once validated in the gas phase, TD-CAM-B3LYP has been used to compute the ESA in chloroform, including solvent effect by the polarizable continuum model (PCM). The predicted OPA and ESA spectra in chloroform are very similar to those in the gas phase, most of the bands shifting by less than 0.1 eV, with a small increase of the intensities and a moderate destabilization of the np state. Finally, ESA spectra have been computed from the minima of the lowest energy pp state, and are consistent with the available experimental transient absorption spectra of the nucleosides in solution, providing a final validation of our computational approach.

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“…Projected atomic orbitals have been shown to give a good description of the virtual space for solvated systems, but also adenosine. 66,74,75 The construction of correlated natural transition orbitals is more costly as they are obtained from excitation vectors of a coupled cluster calculation. In MLCC3 we use CNTOs constructed from CCSD excited states to get a compact description of the excited states.…”

Section: Theorymentioning

confidence: 99%

Oscillator strengths in the framework of equation of motion multilevel CC3

Paul¹,

Folkestad²,

Koch³

2022

Preprint

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We present an efficient implementation of the equation of motion oscillator strengths for the closed-shell multilevel coupled cluster singles and doubles with perturbative triples method (MLCC3) in the electronic structure program e T . The orbital space is split into an active part treated with CC3 and an inactive part computed at the coupled cluster singles and doubles (CCSD) level of theory. Asymptotically, the CC3 contribution scales as O(n V n 3 v n 3 o ) floating-point operations (FLOP), where n V is the total number of virtual orbitals while n v and n o are the number of active virtual and occupied orbitals, respectively. The CC3 contribution, thus, only scales linearly with the full system size and can become negligible compared to the cost of CCSD. We demonstrate the capabilities of our implementation by calculating the UV-VIS spectrum of azobenzene and a core excited state of betaine 30 with more than 1000 molecular orbitals.

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Combining multilevel Hartree–Fock and multilevel coupled cluster approaches with molecular mechanics: a study of electronic excitations in solutions

Abstract: We investigate the coupling of different quantum-embedding approaches with a third molecular-mechanics layer, which can be either polarizable or non-polarizable. In particular, such a coupling is discussed for the multilevel...

Cited by 17 publications

References 127 publications

Excited state absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Excited state absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Transient Absorption of DNA bases in the gas phase and in chloroform solution: a comparative quantum mechanical study

Oscillator strengths in the framework of equation of motion multilevel CC3

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