Extended basis NDDO calculations on diatomic molecules

Gleghorn, J. T.; McConkey, F.W.

doi:10.1007/bf00550972

Cited by 5 publications

(6 citation statements)

References 21 publications

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“…We found that MP2 correlation energies are underestimated and the underestimation increases with the number of basis functions. This finding explains previous reports 61,68 that correlation energies obtained with respect to an NDDO-SEMO reference wave function are far too small. We proposed a local orthogonalization that allowed us to transgress the domain of minimal basis sets and to apply ordinary basis sets in conjunction with the NDDO approximation.…”

Section: Discussionsupporting

confidence: 88%

“…[53][54][55][56][57][58] It was suggested to generalize NDDO-SEMO models to larger, e.g., double-zeta split-valence basis sets to obtain more accurate results. 59 Two studies examined 60,61 the effects of the application of a double-zeta split-valence basis set in conjunction with the NDDO approximation, but came to the conclusion that, contrary to what one would expect, the results did not improve compared to the results obtained with a single-zeta basis set. In this work, we dissect in detail the origins of this counterintuitive observation.…”

Section: Introductionmentioning

confidence: 93%

“…A minimal basis set, however, is generally unsuitable for the description of atoms in molecules because it does not yield reliable relative energies, force constants, electric dipole moments, static dipole polarizabilities, and other properties. − It was suggested to generalize NDDO-SEMO models to larger, e.g., double-ζ split-valence basis sets to obtain more accurate results . Two studies examined , the effects of the application of a double-ζ split-valence basis set in conjunction with the NDDO approximation but came to the conclusion that, contrary to what one would expect, the results did not improve compared to the results obtained with a single-ζ basis set. In this work, we dissect in detail the origins of this counterintuitive observation.…”

Section: Introductionmentioning

confidence: 99%

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Comprehensive Analysis of the Neglect of Diatomic Differential Overlap Approximation

Husch

Reiher

2018

J. Chem. Theory Comput.

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Many modern semiempirical molecular orbital models are built on the neglect of diatomic differential overlap (NDDO) approximation. An in-depth understanding of this approximation is therefore indispensable to rationalize the success of these semiempirical molecular orbital models and to develop further improvements on them. The NDDO approximation provides a recipe to approximate electron-electron repulsion integrals (ERIs) in a symmetrically orthogonalized basis based on a far smaller number of ERIs in a locally orthogonalized basis. We first analyze the NDDO approximation by comparing ERIs in both bases for a selection of molecules and for a selection of basis sets. We find that the errors in Hartree-Fock and second-order Møller-Plesset perturbation theory energies grow roughly linearly with the number of basis functions. We then examine different approaches to correct for the errors caused by the NDDO approximation and propose a strategy to directly correct for them in the two-electron matrices that enter the Fock operator.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Comprehensive Analysis of the Neglect of Diatomic Differential Overlap Approximation

Husch

Reiher

2018

J. Chem. Theory Comput.

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“…An exact orthogonalization of χ H (eg, by the transformation

^{χ} S^{- \frac{1}{2} χ} H^{χ} S^{- \frac{1}{2}}

) was initially attempted, but did not provide a useful model to calculate electronic energies as confirmed by other studies . Kolb and Thiel therefore decided to develop approximate orthogonalization corrections to be added to χ H .…”

Section: The Orthogonalization‐corrected Modelsmentioning

confidence: 99%

“…An exact orthogonalization of χ H (e.g., by the transformation χ S − 1 2 χ H χ S − 1 2 ) was initially attempted, but did not provide a useful model to claculate electroni energies 58,59,182 as confirmed by other studies. 122,154,159,[184][185][186][187] Kolb and Thiel therefore decided to develop approximate orthogonalization corrections to be added to χ H. 58,182 These 58, 59, 151, 182 and other 162,[188][189][190] approximate orthogonalization corrections, are based on an expansion of χ S − 1 2 into a power series,…”

Section: Approximation Of the Symmetrically Orthogonalized One-electr...mentioning

confidence: 99%

Semiempirical molecular orbital models based on the neglect of diatomic differential overlap approximation

Husch

Vaucher

Reiher

2018

Int J of Quantum Chemistry

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Semiempirical molecular orbital (SEMO) models based on the neglect of diatomic differential overlap (NDDO) approximation efficiently solve the self-consistent field equations by rather drastic approximations. The computational efficiency comes at the cost of an error in the electron-electron repulsion integrals. The error may be compensated by the introduction of parametric expressions to evaluate the electron-electron repulsion integrals, the one-electron integrals, and the core-core repulsion. We review the resulting formalisms of popular NDDO-SEMO models (such as the MNDO(/d), AM1, PMx, and OMx models) in a concise and self-contained manner. We discuss the approaches to implicitly and explicitly describe electron correlation effects within NDDO-SEMO models and we dissect strengths and weaknesses of the different approaches in a detailed analysis. For this purpose, we consider the results of recent benchmark studies. Furthermore, we apply bootstrapping to perform a sensitivity analysis for a selection of parameters in the MNDO model. We also identify systematic limitations of NDDO-SEMO models by drawing on an analogy to Kohn-Sham density functional theory. K E Y W O R D SNDDO approximation, semi-empirical methods | INTRODUCTIONThe driving force for the development of semiempirical molecular orbital (SEMO) models has always been the desire to accelerate quantum chemical calculations. At the outset of the development of SEMO models in the middle of the last century, [1][2][3][4][5][6][7][8][9][10] the goal was to carry out electronic structure calculations for small molecules, which was not routinely possible with ab initio electronic structure methods at that time. Since then, theoretical chemistry has seen a remarkable development not only in terms of computational resources but also in terms of ab initio methodology. [11] One must not forget that most electronic structure methods which we apply routinely today, such as Kohn-Sham density functional theory (KS-DFT) [12] and coupled cluster theory, [13] were developed concurrently with today's SEMO models. As a consequence of algorithmic and methodological developments, [11] accurate ab initio electronic structure methods have long replaced SEMO models in their original areas of application (electronic structure calculations for small molecules). Nevertheless, SEMO models did not become extinct. Instead, they opened up different areas of application which can broadly be divided into three categories (see also Ref. [14] for a recent review): (1) simulations of very large systems such as proteins [15][16][17][18][19][20][21][22] and those with thousands of small molecules, [23,24] (2) calculations for a large number of isolated and unrelated medium-sized molecules, for example, in virtual high-throughput screening schemes for materials discovery [25,26] and docking-and-scoring of potential drug candidates, [27][28][29][30][31][32] and (3) entirely new applications such as real-time quantum chemistry where ultra-fast SEMO models allow the perception of visual and h...

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On some ways of modifying semiempirical quantum chemical methods

Zhidomirov

Zhanpeisov

Zilberberg

et al. 1996

Int. J. Quantum Chem.

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rnThe problems of semiempirical quantum chemical calculations of (a) spin densities in paramagnetic organometallics, (b) hydrogen bonds, and (c) bond energies and the structure of transition-metal compounds are discussed. Some modifications of the existing semiempirical quantum chemical method are presented. An extended NDDO approximation has been developed. This scheme includes explicit symmetric orthogonalization of the core Hamiltonian and the use of Hellmann's effective core potential for core-electron interaction. 0 1996 John Wiley & Sons, Inc.

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Extended basis NDDO calculations on diatomic molecules

Cited by 5 publications

References 21 publications

Comprehensive Analysis of the Neglect of Diatomic Differential Overlap Approximation

Comprehensive Analysis of the Neglect of Diatomic Differential Overlap Approximation

Semiempirical molecular orbital models based on the neglect of diatomic differential overlap approximation

On some ways of modifying semiempirical quantum chemical methods

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