The influence of orbital rotation on the energy of closed-shell wavefunctions

Limacher, Peter A.; Kim, Taewon D.; Ayers, Paul W.; Johnson, Paul A.; Baerdemacker, Stijn De; Neck, Dimitri Van; Bultinck, Patrick

doi:10.1080/00268976.2013.874600

Cited by 109 publications

(126 citation statements)

References 28 publications

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“…Prior work has found good agreement generally, [9,11,12] but also some important discrepancies. [38,39] We wish to address this question for system sizes out of reach (due to computational demands) of conventional seniority zero FCI.…”

Section: Energy Comparison Between Doci and Pccdmentioning

confidence: 81%

Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

Shepherd

Henderson

Scuseria

2016

The Journal of Chemical Physics

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Over the past few years pair coupled cluster doubles (pCCD) has shown promise for the description of strong correlation. This promise is related to its apparent ability to match results from doubly occupied configuration interaction (DOCI), even though the latter method has exponential computational cost. Here, by modifying the full configuration interaction quantum Monte Carlo (FCIQMC) algorithm to sample only the seniority zero sector of Hilbert space, we show that the DOCI and pCCD energies are in agreement for a variety of 2D Hubbard models, including for systems well out of reach for conventional configuration interaction algorithms. Our calculations are aided by the sign problem being much reduced in the seniority zero space compared with the full space. We present evidence for this, and then discuss the sign problem in terms of the wave function of the system which appears to have a simplified sign structure.

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Section: Energy Comparison Between Doci and Pccdmentioning

confidence: 81%

Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

Shepherd

Henderson

Scuseria

2016

The Journal of Chemical Physics

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“…Limacher et al 17 have shown that the basisdependent DOCI energy surface has many local minima. To cope with those local minimum problems, we now introduce an orbital optimisation algorithm tailored at locating the global energy minimum.…”

Section: B Orbital Optimisation Algorithmsmentioning

confidence: 99%

“…This method performs particularly well when there are many local energy minima, as in the case of DOCI wave functions. 17 The work flow for the SA procedure pertaining to the orbital optimisation of CI methods is depicted in Fig. 2.…”

Section: Energy Based Orbital Optimisation Through Simulated Annealingmentioning

confidence: 99%

Polynomial scaling approximations and dynamic correlation corrections to doubly occupied configuration interaction wave functions

Raemdonck

Alcoba

Poelmans

et al. 2015

The Journal of Chemical Physics

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A class of polynomial scaling methods that approximate Doubly Occupied Configuration Interaction (DOCI) wave functions and improve the description of dynamic correlation is introduced. The accuracy of the resulting wave functions is analysed by comparing energies and studying the overlap between the newly developed methods and full configuration interaction wave functions, showing that a low energy does not necessarily entail a good approximation of the exact wave function. Due to the dependence of DOCI wave functions on the single-particle basis chosen, several orbital optimisation algorithms are introduced. An energy-based algorithm using the simulated annealing method is used as a benchmark. As a computationally more affordable alternative, a seniority number minimising algorithm is developed and compared to the energy based one revealing that the seniority minimising orbital set performs well. Given a well-chosen orbital basis, it is shown that the newly developed DOCI based wave functions are especially suitable for the computationally efficient description of static correlation and to lesser extent dynamic correlation. C 2015 AIP Publishing LLC. [http://dx

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“…A different, computationally feasible approach suitable for strongly-correlated systems uses seniority-zero wavefunctions to describe the static/nondynamic part of the electron correlation en-ergy. [31][32][33][34][35][36][37][38][39][40][41][42][43][44] The missing dynamic electron correlation effects are included a posteriori in these ansätze using, for instance, many-body perturbation theory [45][46][47], coupled-cluster theory [48][49][50][51][52], extended random phase approximation [53], and density functional theory (DFT) corrections [54,55].…”

Section: Introductionmentioning

confidence: 99%

Benchmark of Dynamic Electron Correlation Models for Seniority-Zero Wave Functions and Their Application to Thermochemistry

Boguslawski

Tecmer

2017

J. Chem. Theory Comput.

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Wavefunctions restricted to electron-pair states are promising models to describe static/nondynamic electron correlation effects encountered, for instance, in bond-dissociation processes and transition-metal and actinide chemistry. To reach spectroscopic accuracy, however, the missing dynamic electron correlation effects that cannot be described by electron-pair states need to be included a posteriori. In this article, we extend the previously presented perturbation theory models with an Antisymmetric Product of 1-reference orbital Geminal (AP1roG) reference function that allow us to describe both static/nondynamic and dynamic electron correlation effects. Specifically, our perturbation theory models combine a diagonal and off-diagonal zero-order Hamiltonian, a single-reference and multi-reference dual state, and different excitation operators used to construct the projection manifold. We benchmark all proposed models as well as an a posteriori linearized coupled cluster correction on top of AP1roG against CR-CCSD(T) reference data for reaction energies of several closed-shell molecules that are extrapolated to the basis set limit. Moreover, we test the performance of our new methods for multiple bond breaking processes in the N2, C2, and BN dimers against MRCI-SD and MRCI-SD+Q reference data. Our numerical results indicate that the best performance is obtained from a linearized coupled cluster correction as well as second-order perturbation theory corrections employing a diagonal and off-diagonal zero-order Hamiltonian and a single-determinant dual state. These dynamic corrections on top of AP1roG allow us to reliably model molecular systems dominated by static/nondynamic as well as dynamic electron correlation.

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The influence of orbital rotation on the energy of closed-shell wavefunctions

Cited by 109 publications

References 28 publications

Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

Using full configuration interaction quantum Monte Carlo in a seniority zero space to investigate the correlation energy equivalence of pair coupled cluster doubles and doubly occupied configuration interaction

Polynomial scaling approximations and dynamic correlation corrections to doubly occupied configuration interaction wave functions

Benchmark of Dynamic Electron Correlation Models for Seniority-Zero Wave Functions and Their Application to Thermochemistry

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