A full CI algorithm on the CRAY T3D. Application to the NH3 molecule

Evangelisti, Stefano; Bendazzoli, Gian Luigi; Ansaloni, Roberto; Rossi, Elda

doi:10.1016/0009-2614(94)01461-4

Cited by 27 publications

(9 citation statements)

References 17 publications

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“…Fortunately, both algorithmic advances [8][9][10][11][12][13][14][15] and improvements in computer hardware have made full CI benchmarks less computationally expensive. Whereas full CI benchmarking in the 1980s and early 1990s focused almost exclusively on single-point energies, it is now possible to perform geometry optimizations and even frequency analysis for very small molecules using full CI to examine the effect of higher-order correlation on molecular properties.…”

Section: Introductionmentioning

confidence: 99%

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

Abrams

Sherrill

2003

The Journal of Chemical Physics

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We compare several standard polarized double-zeta basis sets for use in full configuration interaction benchmark computations. The 6-31G**, DZP, cc-pVDZ, and Widmark-Malmqvist-Roos atomic natural orbital ͑ANO͒ basis sets are assessed on the basis of their ability to provide accurate full configuration interaction spectroscopic constants for several small molecules. Even though highly correlated methods work best with larger basis sets, predicted spectroscopic constants are in good agreement with experiment; bond lengths and harmonic vibrational frequencies have average absolute errors no larger than 0.017 Å and 1.6%, respectively, for all but the ANO basis. For the molecules considered, 6-31G** gives the smallest average errors, while the ANO basis set gives the largest. The use of variationally optimized basis sets and natural orbitals are also explored for improved benchmarking. Although optimized basis sets do not always improve predictions of molecular properties, taking a DZP-sized subset of the natural orbitals from a singles and doubles configuration interaction computation in a larger basis significantly improves results.

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Section: Introductionmentioning

confidence: 99%

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

Abrams

Sherrill

2003

The Journal of Chemical Physics

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“…The concept of approximating or averaging diagonal matrix elements to enhance algorithmic performance or preserve spin properties has existed in the literature for some time. 14,44 Recently, Evangelisti et al 16,38 have suggested several schemes that enable efficient on-the-fly evaluation of average diagonal Hamiltonian elements, thus eliminating the need to store the entire diagonal vector on disk or in core memory. The first approach 38 is simply to use the sum of orbital energies ( i ) of the occupied orbitals for each determinant, a relatively crude estimate, which, unlike eq.…”

Section: Approximate Diagonal Elementsmentioning

confidence: 99%

Systematic Study of Selected Diagonalization Methods for Configuration Interaction Matrices

et al. 2001

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Several modifications to the Davidson algorithm are systematically explored to establish their performance for an assortment of configuration interaction (CI) computations. The combination of a generalized Davidson method, a periodic two-vector subspace collapse, and a blocked Davidson approach for multiple roots is determined to retain the convergence characteristics of the full subspace method. This approach permits the efficient computation of wave functions for large-scale CI matrices by eliminating the need to ever store more than three expansion vectors (b i ) and associated matrix-vector products (σ i ), thereby dramatically reducing the I/O requirements relative to the full subspace scheme. The minimal-storage, single-vector method of Olsen is found to be a reasonable alternative for obtaining energies of well-behaved systems to within µE h accuracy, although it typically requires around 50% more iterations and at times is too inefficient to yield high accuracy (ca. 10−10 E h ) for very large CI problems. Several approximations to the diagonal elements of the CI Hamiltonian matrix are found to allow simple on-the-fly computation of the preconditioning matrix, to maintain the spin symmetry of the determinant-based wave function, and to preserve the convergence characteristics of the diagonalization procedure.

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“…45 Two additional molecules, NH 3 and CH 2 , have been chosen for the availability of FCI benchmark calculations. 46,19 For the diatomics, the basis set was a standard Huzinaga 47 47,48 has been used as in the FCI calculation by Bauschlicher and Taylor 51 with six d functions for C. The two core MOs as well as the two highest virtuals have been frozen in all cases but for BeO where only one core and virtual were frozen. The N and C core MOs were frozen in NH 3 and CH 2 .…”

Section: Equilibrium Region Calculationsmentioning

confidence: 99%

Assessment for the mean value total dressing method: Comparison with coupled cluster including triples methods for BF, NO+, CN+, C2, BeO, NH3, CH2, H2O, BH, HF, SiH2, Li2, LiNa, LiBe+, NeH+, and O3

Garcia-Cuesta

Sánchez‐Marín

Merás

et al. 1997

The Journal of Chemical Physics

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Limited previous experience with the mean value total dressing ͑MVTD͒ method had shown that MVTD energies for closed shell systems are generally better than CCSD͑T͒ ones compared to FCI. The method, previously published as total dressing 2Ј(td-2Ј), is based on the single reference intermediate Hamiltonian theory. It is not a CC method but deals in a great part with the same physical effects that CC methods that incorporate amplitudes of triples such as CCSDT or its CCSDT-1n approaches. A number of test calculations comparing to diverse CC methods, as well as FCI and experiment when available, have been performed. The tests concern equilibrium energies in NH 3 and CH 2 , equilibrium energies and distances in some diatomics ͑BF, NO ϩ , CN ϩ , C 2 , BeO͒, different bond breaking situations ͑H 2 O, BH, HF, SiH 2 ͒ and spectroscopic properties of different bonding conditions ͑Li 2 , LiNa, LiBe ϩ , NeH ϩ , and O 3 ͒. The results are in general closer to the full CCSDT ones in the equilibrium regions and close to CCSDT-1 along most dissociation curves. A few exceptions to this rule are analyzed with the help of an approach to MVTD that does not take into account the effects of linked quadriexcitations. Such analysis suggests the interest of improving the treatment of effects of linked triples in the MVTD model. The separate contributions of linked and unlinked triples and quadruples are also analyzed for some of the above diatomics representing different behaviors of bond breaking. The interest of such analysis is illustrated in the NeH ϩ molecule. The MVTD results show, in general, a high quality, provided that the nature of the correlation problem does not become largely multiconfigurational, as occurs in multiple bond dissociation or in the asymmetric stretching of ozone.

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A full CI algorithm on the CRAY T3D. Application to the NH3 molecule

Cited by 27 publications

References 17 publications

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

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

Systematic Study of Selected Diagonalization Methods for Configuration Interaction Matrices

Assessment for the mean value total dressing method: Comparison with coupled cluster including triples methods for BF, NO+, CN+, C2, BeO, NH3, CH2, H2O, BH, HF, SiH2, Li2, LiNa, LiBe+, NeH+, and O3

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