Journal ArticleDOI
Multireference coupled-cluster theory: The easy way
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The multi-ionization equation-of-motion coupled-cluster (CC) method is developed for multireference (MR) problems, depending upon a formal matrix diagonalization step to define the coefficients in the wavefunction in an unbiased way that allows for important MR character.Abstract:
The multi-ionization equation-of-motion coupled-cluster (CC) method is developed for multireference (MR) problems. It is operationally single reference, depending upon a formal matrix diagonalization step to define the coefficients in the wavefunction in an unbiased way that allows for important MR character. The method is illustrated for the autoisomerization of cyclobutadiene, which has a very large multireference effect and compared to other MR-CC results. The newly implemented methods are also used to obtain the vertical double ionization (DI) potentials of several small molecules (H2O, CO, C2H2, C2H4). Also, the performance of the new methods is analyzed by plotting the potential energy curve for twisted ethylene as a function of a dihedral angle between two methylenes. Evaluation of the total molecular energy via MR-DI-CC calculations makes it possible to avoid an unphysical cusp.read more
Citations
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The theory of variational hybrid quantum-classical algorithms
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Multireference nature of chemistry: the coupled-cluster view.
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Quantum Mechanical Studies on the Photophysics and the Photochemistry of Nucleic Acids and Nucleobases
TL;DR: This review provides a concise, complete picture of the computational studies carried out, approximately, in the past decade on the photophysics of DNA nucleobases in the gas phase and in solution.
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Magnetic interactions in molecules and highly correlated materials: physical content, analytical derivation, and rigorous extraction of magnetic Hamiltonians.
TL;DR: Physical Content, Analytical Derivation, and Rigorous Extraction of Magnetic Hamiltonians Jean Paul Malrieu, Rosa Caballol, Carmen J. Calzado, Coen de Graaf, and Nathalie Guiheŕy.
Journal ArticleDOI
Coupled‐cluster theory and its equation‐of‐motion extensions
TL;DR: This brief overview of coupled‐cluster theory will describe formal aspects of the theory which should be understood by perspective users of CC methods and comment on some current developments that are improving the theory's accuracy or applicability.
References
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Gaussian Basis Functions for Use in Molecular Calculations. III. Contraction of (10s6p) Atomic Basis Sets for the First‐Row Atoms
TL;DR: In this paper, the effects of contraction on the energies and one-electron properties of the water and nitrogen molecules were investigated, and the authors obtained principles which can be used to predict optimal contraction schemes for other systems without the necessity of such exhaustive calculations.
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Coupled-cluster theory in quantum chemistry
Rodney J. Bartlett,Monika Musiał +1 more
TL;DR: In this article, the essential aspects of coupled-cluster theory are explained and illustrated with informative numerical results, showing that the theory offers the most accurate results among the practical ab initio electronic-structure theories applicable to moderate-sized molecules.
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The iterative calculation of a few of the lowest eigenvalues and corresponding eigenvectors of large real-symmetric matrices
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The equation of motion coupled‐cluster method. A systematic biorthogonal approach to molecular excitation energies, transition probabilities, and excited state properties
TL;DR: In this paper, a comprehensive overview of the equation of motion coupled-cluster (EOM•CC) method and its application to molecular systems is presented by exploiting the biorthogonal nature of the theory, it is shown that excited state properties and transition strengths can be evaluated via a generalized expectation value approach that incorporates both the bra and ket state wave functions.
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Coupled-cluster method for multideterminantal reference states
TL;DR: In this paper, a general coupled-cluster method valid for arbitrary multideterminantal reference states is formulated and the resulting cluster expansion for the wave function is a generalization of that introduced by Silverstone and Sinano and applied by Sinano\ifmmode \check{g}else \v{g}\fi{}lu and collaborators.