The Spin–Spin Coupling Constants in Ethane, Methanol and Methylamine: A Comparison of DFT, MCSCF and CCSD Results

Pecul, Magdalena; Helgaker, Trygve

doi:10.3390/i4030143

Cited by 40 publications

(26 citation statements)

References 35 publications

(61 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In some cases [57], B3LYP and MP2 gave very similar results but rather different from those obtained at the CCSD level or experimentally. In other cases [53][54][55][56], B3LYP provided satisfactory results compared with the MP2, QCISD and CCSD ones. Thus, because of the probable influence of the conformation on the vertical ionization potentials, it was decided to check the nature and number of "low" energy conformations as a function of the calculation level.…”

Section: Influence Of the Electronic Correlation Description Levelmentioning

confidence: 90%

“…This was due to the fact that the electronic correlation is not the same for all the conformations as was also emphasized for dipeptides [49]. In the literature, the quality of B3LYP was often analyzed as compared with other correlated levels [50][51][52][53][54][55][56][57]. The B3LYP level was found unsuited to study transition metal complexes [50,51] or diradical species [52] but gave very satisfactory bond distances in metallocenes [55].…”

Section: Influence Of the Electronic Correlation Description Levelmentioning

confidence: 99%

See 1 more Smart Citation

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Dehareng

Dive

2004

IJMS

View full text Add to dashboard Cite

Vertical ionization energies (IE) as a function of the conformation are determined at the quantum chemistry level for eighteen α-L-amino acids. Geometry optimization of the neutrals are performed within the Density Functional Theory (DFT) framework using the hybrid method B3LYP and the 6-31G**(5d) basis set. Few comparisons are made with wave-function-based ab initio correlated methods like MP2, QCISD or CCSD. For each amino acid, several conformations are considered that lie in the range 10-15 kJ/mol by reference to the more stable one. Their IE are calculated using the Outer-Valence-Green's-Functions (OVGF) method at the neutrals' geometry. Few comparisons are made with MP2 and QCISD IE. It turns out that the OVGF results are satisfactory but an uncertainty relative to the most stable conformer at the B3LYP level persists. Moreover, the value of the IE can largely depend on the conformation due to the fact that the ionized molecular orbitals (MO) can change a lot as a function of the nuclear structure.

show abstract

Section: Influence Of the Electronic Correlation Description Levelmentioning

confidence: 90%

Section: Influence Of the Electronic Correlation Description Levelmentioning

confidence: 99%

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Dehareng

Dive

2004

IJMS

View full text Add to dashboard Cite

show abstract

“…b From Ref. [73]. c Experimental data known in the literature are from very old studies and are taken from Refs [7,73,74].…”

Section: Figurementioning

confidence: 99%

Complete basis set prediction of methanol isotropic nuclear magnetic shieldings and indirect nuclear spin–spin coupling constants (SSCC) using polarization‐consistent and XZP basis sets and B3LYP and BHandH density functionals

Kupka¹

2009

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

Efficient B3LYP and BHandH density functionals were used to estimate methanol's nuclear magnetic isotropic shieldings and spin-spin coupling constants in the basis set limit. Polarization-consistent pcS-n and pcJ-n (n = 0, 1, 2, 3 and 4), and segmented contracted XZP, where X = D, T, Q and 5, basis sets were used and the results fitted with simple mathematical formulas. The performance of the methods was assessed from comparison with experiment and higher level calculations. 1J(CH) and 3J(HH) values were determined from very diluted solutions in deuterochloroform and compared with theoretical predictions. The agreement between complete basis set (CBS) density functional theory (DFT) predicted isotropic shieldings and spin-spin values and experiment was good. The BHandH/pcS-n methanol shieldings obtained using structures optimized at the same level of theory are approaching the accuracy of the advanced coupled-cluster-singles-doubles-approximate triples (CCSD(T)) calculations.

show abstract

“…All the four contributions to spin-spin coupling 37 -41 (FC, spin dipolar, orbital diamagnetic, and orbital paramagnetic) were obtained using CP/DFT as implemented in the Gaussian03 suite of programs. 42 In a comparison of DFT, MCSCF, and CCSD results in ethane, methanol, and methylamine, Pecul and Helgaker 43 found that DFT methods perform well for the geminal coupling 2 J H,H 0 , but tend to overestimate vicinal H-H coupling constants. The basis set dependence of geminal H-H coupling in methane and substituted hydrocarbons has been extensively investigated.…”

Section: Scalar J-coupling Based On Cp/dft Methodsmentioning

confidence: 99%

DFT studies of the conformational/structural dependencies of geminal ¹H,¹H scalar coupling ²J(H,H′) in substituted methanes

Barfield¹

2007

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

A study is presented of the structural dependencies for scalar, interproton J-coupling across two bonds in a series of substituted methanes. The coupled perturbed, density functional theory method with a B3PW91 functional and aug-cc-pVTZ-J basis sets is used to examine coupling between geminal protons (2)J(H,H') in methane and a series of substituted compounds CH(3)X (X = CH3, CH(2)CH(3), CH=CH2, CH=O, and NH2) as functions of the dihedral angle phi measured about the C1-X2 bonds. All four contributions are obtained but all conformational effects are dominated by the Fermi contact term. Simple linear combination of atomic orbitals (LCAO)-molecular orbital (MO) sum-over-states methods are used to examine the relationships of the coupling constants with dihedral angles as well as internal H-C-H and H-C1-X2 angles. This study explores some novel aspects of geminal H-H coupling including an analysis of the asymmetry in the conformational dependencies arising from non-next-nearest neighbor interactions. For each of the substituted methanes, explicit trigonometric/exponential expressions are given and these accurately reproduce the (2)J(H,H') structural dependencies with standard deviations usually less than 0.03 Hz. The molecular structures for representative bicyclic molecules were fully optimized, and DFT results for (2)J(H,H') reproduce all the trends in the experimental data. A discussion is given on the applicability of the equations for H--H coupling in the substituted methanes to coupling in the bicyclic molecules.

show abstract

The Spin–Spin Coupling Constants in Ethane, Methanol and Methylamine: A Comparison of DFT, MCSCF and CCSD Results

Cited by 40 publications

References 35 publications

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Complete basis set prediction of methanol isotropic nuclear magnetic shieldings and indirect nuclear spin–spin coupling constants (SSCC) using polarization‐consistent and XZP basis sets and B3LYP and BHandH density functionals

DFT studies of the conformational/structural dependencies of geminal ¹H,¹H scalar coupling ²J(H,H′) in substituted methanes

Contact Info

Product

Resources

About

The Spin–Spin Coupling Constants in Ethane, Methanol and Methylamine: A Comparison of DFT, MCSCF and CCSD Results

Cited by 40 publications

References 35 publications

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

Complete basis set prediction of methanol isotropic nuclear magnetic shieldings and indirect nuclear spin–spin coupling constants (SSCC) using polarization‐consistent and XZP basis sets and B3LYP and BHandH density functionals

DFT studies of the conformational/structural dependencies of geminal 1H,1H scalar coupling 2J(H,H′) in substituted methanes

Contact Info

Product

Resources

About

DFT studies of the conformational/structural dependencies of geminal ¹H,¹H scalar coupling ²J(H,H′) in substituted methanes