A comparison of polarized double-zeta basis sets and natural orbitals for full configuration interaction benchmarks

Abrams, Micah L.; Sherrill, C. David

doi:10.1063/1.1532313

Cited by 40 publications

(44 citation statements)

References 39 publications

(21 reference statements)

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“…Since their introduction in 1955, the NOs have been used extensively in CI calculations. [12][13][14][15][16] Several procedures of generating NOs have been exploited. Alternatively, one may use NOs to define an active space and include all the configurations ͑as specified by the correlation method͒ within this active space.…”

Section: Introductionmentioning

confidence: 99%

Frozen natural orbitals for ionized states within equation-of-motion coupled-cluster formalism

Landau

Khistyaev

Dolgikh

et al. 2010

The Journal of Chemical Physics

124

136

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The frozen natural orbital (FNO) approach, which has been successfully used in ground-state coupled-cluster calculations, is extended to open-shell ionized electronic states within equation-of-motion coupled-cluster (EOM-IP-CC) formalism. FNOs enable truncation of the virtual orbital space significantly reducing the computational cost with a negligible decline in accuracy. Implementation of the MP2-based FNO truncation scheme within EOM-IP-CC is presented and benchmarked using ionized states of beryllium, dihydrogen dimer, water, water dimer, nitrogen, and uracil dimer. The results show that the natural occupation threshold, i.e., percentage of the total natural occupation recovered in the truncated virtual orbital space, provides a more robust truncation criterion as compared to the fixed percentage of virtual orbitals retained. Employing 99%-99.5% natural occupation threshold, which results in the virtual space reduction by 70%-30%, yields errors below 1 kcal/mol. Moreover, the total energies exhibit linear dependence as a function of the percentage of the natural occupation retained allowing for extrapolation to the full virtual space values. The capabilities of the new method are demonstrated by the calculation of the 12 lowest vertical ionization energies (IEs) and the lowest adiabatic IE of guanine. In addition to IE calculations, we present the scans of potential energy surfaces (PESs) for ionized (H(2)O)(2) and (H(2))(2). The scans demonstrate that the FNO truncation does not introduce significant nonparallelity errors and accurately describes the PESs shapes and the corresponding energy differences, e.g., dissociation energies.

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Section: Introductionmentioning

confidence: 99%

Frozen natural orbitals for ionized states within equation-of-motion coupled-cluster formalism

Landau

Khistyaev

Dolgikh

et al. 2010

The Journal of Chemical Physics

124

136

View full text Add to dashboard Cite

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“…[39] b Ref. [39] are known to lead to significant errors, of ∼ 10 mE h , in the calculated fixed-node ground-state energy [40]. (This error is largely removed when multi-determinant trial wave functions are used to account for the near degeneracy.…”

Section: All-electron Total Ground-state Energiesmentioning

confidence: 99%

“…Optimized SlaterJastrow trial wave functions with a single determinant (1) a Ref. [39] b Ref. [39] are known to lead to significant errors, of ∼ 10 mE h , in the calculated fixed-node ground-state energy [40].…”

Section: All-electron Total Ground-state Energiesmentioning

confidence: 99%

Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis

Al-Saidi

Zhang

Krakauer

2006

The Journal of Chemical Physics

168

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We extend the recently introduced phaseless auxiliary-field quantum Monte Carlo (QMC) approach to any single-particle basis, and apply it to molecular systems with Gaussian basis sets. QMC methods in general scale favorably with system size, as a low power. A QMC approach with auxiliary fields in principle allows an exact solution of the Schrödinger equation in the chosen basis. However, the well-known sign/phase problem causes the statistical noise to increase exponentially. The phaseless method controls this problem by constraining the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. In the present calculations, the trial wave function is a single Slater determinant from a Hartree-Fock calculation. The calculated all-electron total energies show typical systematic errors of no more than a few milli-Hartrees compared to exact results. At equilibrium geometries in the molecules we studied, this accuracy is roughly comparable to that of coupled-cluster with single and double excitations and with non-iterative triples, CCSD(T). For stretched bonds in H2O, our method exhibits better overall accuracy and a more uniform behavior than CCSD(T).

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“…We can see it for some diatomics in the Table 2. Analogously, we can compare the APSGF results with reference full CI results with the same basis set 77. In some cases (BH, NH + ) the full CI calculated equilibrium distances are better, while in other cases (CH + , HF) the APSGF results are closer to the experimental ones.…”

Section: Resultsmentioning

confidence: 81%

Electron group functions for the analysis of the electronic structures of molecules

Tokmachev

Dronskowski

2005

J Comput Chem

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The electronic structure of a vast majority of molecular systems can be understood in terms of electron groups and their wave functions. They serve as a natural basis for bringing intuitive chemical and physical concepts into quantum chemical calculations. This article considers the general electron group functions formalism as well as its simple geminal version. We try to characterize the wave function with the group structure and its capabilities in actual calculations. For this purpose we implement a variational method based on the wave function in the form of an antisymmetrized product of strongly orthogonal group functions and perform a series of electronic structure calculations for small molecules and model systems. The most important point studied is the relation between the choice of electron groups and the results obtained. We consider energetic characteristics as well as optimal geometry parameters. In view of practical importance, the structure of variationally optimized local one-electron states is considered in detail as well as intuitive characteristics of chemical bonds.

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A comparison of polarized double-zeta basis sets and natural orbitals for full configuration interaction benchmarks

Cited by 40 publications

References 39 publications

Frozen natural orbitals for ionized states within equation-of-motion coupled-cluster formalism

Frozen natural orbitals for ionized states within equation-of-motion coupled-cluster formalism

Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis

Electron group functions for the analysis of the electronic structures of molecules

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