The effect of lone pairs and electronegativity on the indirect nuclear spin–spin coupling constants in CH2X (X=CH2, NH, O, S): <i>Ab initio</i> calculations using optimized contracted basis sets

Provasi, Patricio F.; Aucar, Gustavo A.; Sauer, Stephan P. A.

doi:10.1063/1.1379331

Cited by 261 publications

(143 citation statements)

References 60 publications

(11 reference statements)

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“…Basis functions with angular momenta up to g are supported. Predictions of good accuracy for J-couplings can be obtained [106,107] especially when using specialised basis sets [108][109][110][111], several of which have been added to the basis set library.…”

Section: Electric and Magnetic Molecular Propertiesmentioning

confidence: 99%

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Shao¹,

Gan²,

Epifanovsky³

et al. 2014

Molecular Physics

2,707

2,077

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A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and openshell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr 2 dimer, exploring zeolitecatalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.Keywords quantum chemistry, software, electronic structure theory, density functional theory, electron correlation, computational modelling, Q-Chem Disciplines Chemistry CommentsThis article is from Molecular Physics: An International Journal at the Interface Between Chemistry and Physics 113 (2015): 184, doi:10.1080/00268976.2014. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Authors 185A summary of the technical advances that are incorporated in the fourth major release of the Q-CHEM quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly corre...

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Section: Electric and Magnetic Molecular Propertiesmentioning

confidence: 99%

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Shao¹,

Gan²,

Epifanovsky³

et al. 2014

Molecular Physics

2,707

2,077

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“…A range of special basis sets have been developed that augment those used in typical calculations with higher exponent (tight) Gaussian functions. Examples of such sets are the aug-cc-pVXZ-J sets of Sauer et al [34,35], the augmented sets of Helgaker et al [36], the ccJ-pVNZ sets of Benedikt et al [37], and the pcJ-N basis sets of Jensen [38].…”

Section: Computational Detailsmentioning

confidence: 99%

Molecular properties in the Tamm–Dancoff approximation: indirect nuclear spin–spin coupling constants

et al. 2015

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The Tamm-Dancoff approximation (TDA) can be applied to the computation of excitation energies using time-dependent Hartree-Fock (TD-HF) and time-dependent density-functional theory (TD-DFT). In addition to simplifying the resulting response equations, the TDA has been shown to significantly improve the calculation of triplet excitation energies in these theories, largely overcoming issues associated with triplet instabilities of the underlying reference wave functions. Here, we examine the application of the TDA to the calculation of another response property involving triplet perturbations, namely the indirect nuclear spin-spin coupling constant. Particular attention is paid to the accuracy of the triplet spin-dipole and Fermi-contact components. The application of the TDA in HF calculations leads to vastly improved results. For DFT calculations, the TDA delivers improved stability with respect to geometrical variations but does not deliver higher accuracy close to equilibrium geometries. These observations are rationalized in terms of the ground-and excited-state potential energy surfaces and, in particular, the severity of the triplet instabilities associated with each method. A notable feature of the DFT results within the TDA is their similarity across a wide range of different functionals. The uniformity of the TDA results suggests that some conventional evaluations may exploit error cancellations between approximations in the functional forms and those arising from triplet instabilities. The importance of an accurate treatment of correlation for evaluating spin-spin coupling constants is highlighted by this comparison.

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“…to use basis sets optimized for coupling constant calculations [14][15][16] only on the atoms of interest whereas using smaller standard basis sets on the other atoms. Secondly, we have developed smaller optimized basis sets for coupling constant calculations [16] by contracting the s-and p-type functions in large optimized basis sets [15] with molecular orbital coefficients from self-consistent field calculations on the corresponding hydride molecules AH n . These two options can be combined in order to increase the maximal size of molecules in coupling constant calculations without a significant loss of accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, we proposed recently the use of locally dense basis sets in the calculation of spin-spin coupling constants [12,13], i.e. to use basis sets optimized for coupling constant calculations [14][15][16] only on the atoms of interest whereas using smaller standard basis sets on the other atoms. Secondly, we have developed smaller optimized basis sets for coupling constant calculations [16] by contracting the s-and p-type functions in large optimized basis sets [15] with molecular orbital coefficients from self-consistent field calculations on the corresponding hydride molecules AH n .…”

Section: Introductionmentioning

confidence: 99%

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

Provasi

Aucar

Sauer

2003

IJMS

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Ab initio calculations of the spin-spin coupling constants have been carried out for methan-and ethanimine, methanal-and ethanaloxime at the level of the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes (SOPPA(CCSD)) using the aug-cc-pVTZ-J basis sets. Previously we have shown that this method can reproduce quantitatively the coupling constants for methanimine; our new results for methanal-and ethanaloxime agree also very well with the measured couplings. A study of both purely geometrical and substituent effects on all coupling constants in the title compounds is presented. Analyzing the four contributions to the coupling constants we find that the stereoelectronic effect of the nitrogen lone pair on the one-bond C-H and C-C couplings as well as the corresponding effect for the geminal N-H and N-C couplings is affected strongly by the -OH substituent. For the one-bond C-N couplings we observe that the orbital paramagnetic (OP) contribution is comparable to the Fermi Contact (FC) contribution but opposite in sign and that the spin-dipolar (SD) term amounts to between 40% and 85% of the total coupling constants. Changes in the total one-bond C-N couplings caused by the -OH substituent are also almost entirely due to SD contribution.

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The effect of lone pairs and electronegativity on the indirect nuclear spin–spin coupling constants in CH2X (X=CH2, NH, O, S): Ab initio calculations using optimized contracted basis sets

Cited by 261 publications

References 60 publications

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Molecular properties in the Tamm–Dancoff approximation: indirect nuclear spin–spin coupling constants

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

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