Demonstrating that the nonorthogonal orbital optimized coupled cluster model converges to full configuration interaction
نویسندگان
چکیده
منابع مشابه
Coupled-cluster and configuration-interaction calculations for heavy nuclei.
We compare coupled-cluster (CC) and configuration-interaction (CI) results for (56)Ni obtained in the pf-shell basis, focusing on practical CC approximations that can be applied to systems with dozens or hundreds of correlated fermions. The weight of the reference state and the strength of correlation effects are controlled by the gap between the f(7/2) orbit and the f(5/2), p(3/2), p(1/2) orbi...
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An efficient full-configuration-interaction nuclear orbital treatment has been recently developed as a benchmark quantum-chemistry-like method to calculate ground and excited "solvent" energies and wave functions in small doped DeltaE(est) clusters (N < or = 4) [M. P. de Lara-Castells, G. Delgado-Barrio, P. Villarreal, and A. O. Mitrushchenkov, J. Chem. Phys. 125, 221101 (2006)]. Additional met...
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Using a Lagrangian-based approach, we present a more elegant derivation of the equations necessary for the variational optimization of the molecular orbitals (MOs) for the coupled-cluster doubles (CCD) method and second-order Møller-Plesset perturbation theory (MP2). These orbital-optimized theories are referred to as OO-CCD and OO-MP2 (or simply "OD" and "OMP2" for short), respectively. We als...
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which is a linear combination of n-electron configurations, or determinants, with coefficients equal to c!. The components |Φ! form an orthonormal basis of the wavefunction. The determinants are the set of features that comprise the wavefunction, so we can optimize them by minimizing the electronic energy. To determine the energy of the wavefunction c, the Schrödinger equation in matrix form reads
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The nondynamical correlation energy may be defined as the difference between full configuration interaction within the space of all valence orbitals and a single determinant of molecular orbitals ~Hartree–Fock theory!. In order to describe bond breaking, diradicals, and other electronic structure problems where Hartree–Fock theory fails, a reliable description of nondynamical correlation is ess...
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ژورنال
عنوان ژورنال: The Journal of Chemical Physics
سال: 2018
ISSN: 0021-9606,1089-7690
DOI: 10.1063/1.5006160