Chemical Notions from the Electron Density

Rico, J. Fernández; López, Rafael; Ema, I.; Ramı́rez, G.

doi:10.1021/ct0500951

Cited by 27 publications

(25 citation statements)

References 74 publications

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“…but, what can be more important, it provides density-force-energy relations, which are able to give support on first principles to all the intuitive concepts of empirical structural chemistry. 6 As it is well known, this theorem is strictly fulfilled by the exact solutions and by certain types of variational approximations. In the latter case, the sufficiency conditions for its strict fulfillment were first studied by Hurley 7 and next reformulated by other authors.…”

Section: Introductionmentioning

confidence: 88%

Generation of basis sets with high degree of fulfillment of the Hellmann‐Feynman theorem

et al. 2007

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A direct relationship is established between the degree of fulfillment of the Hellman-Feynman (electrostatic) theorem, measured as the difference between energy derivatives and electrostatic forces, and the stability of the basis set, measured from the indices that characterize the distance of the space generated by the basis functions to the space of their derivatives with respect to the nuclear coordinates. On the basis of this relationship, a criterion for obtaining basis sets of moderate size with a high degree of fulfillment of the theorem is proposed. As an illustrative application, previously reported Slater basis sets are extended by using this criterion. The resulting augmented basis sets are tested on several molecules finding that the differences between energy gradient and electrostatic forces are reduced by at least one order of magnitude.

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Section: Introductionmentioning

confidence: 88%

Generation of basis sets with high degree of fulfillment of the Hellmann‐Feynman theorem

et al. 2007

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“…Further, the MESP topographical features such as eigenvalues and eigenvectors of the corresponding Hessian matrix were found to be significantly different from those corresponding to the π‐electron localization/delocalization . The minimum value of MESP in the lone pair region indicated the electron‐rich character of the lone pair, which showed variation in magnitude for a given atom, for a limited number of test molecules studied by them …”

Section: Introductionmentioning

confidence: 91%

“…Lone pairs, π‐bonds, and π‐electron delocalization exhibit a topographical feature of the (3, +3) CP ( V min ) . According to the MESP criteria, one of the eigenvectors of the Hessian matrix corresponding to a lone pair always points in the direction of the lone‐pair‐bearing atom and one of the eigenvalues necessarily shows a significantly larger magnitude than the other two …”

Section: Introductionmentioning

confidence: 99%

Electrostatics for probing lone pairs and their interactions

2017

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The value of the molecular electrostatic potential minimum (V ) and its topographical features (position, as well as the eigenvalues and eigenvectors of the corresponding Hessian matrix) are recently proposed as the criteria for characterizing a lone pair (Kumar A. et al., J. Phys. Chem. 2014, A118, 526). This electrostatic characterization of lone pairs is examined for a large number of small molecules employing MP4/6-311++G(d,p)//MP2/6-311++G(d,p) theory. The eigenvector of the Hessian matrix corresponding to its largest eigenvalue (λ ), is found to be directed toward the lone pair-bearing-atom, with λ showing a strong linear correlation with V . Large magnitudes of V and λ indicate a charge-dense lone pair. The topographical features of V are seen to provide insights into the interactive behavior of the molecules with model electrophiles, viz. HF, CO , and Li . In all the complexes of HF and majority of the other complexes, the interaction energy (E ) correlates well with the respective V value, but for some deviations occurring due to other competing secondary interactions. The electrostatic interactions are found to be highly directional in nature as the orientation of interacting atom correlates strongly to the position of lone pair. In summary, the present study on a large number of test molecules shows that electrostatics is able to probe lone pairs in molecules and offers a simple interpretation of chemical reactivity. © 2017 Wiley Periodicals, Inc.

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“…Once the partition is done, different modules can be accessed to compute density, density deformations [30], electrostatic potential and field, Hellmann-Feynman forces, radial factors of fragments expansion and locally oriented multipoles. 2D and 3D grids can be generated and visualized with the built-in viewers.…”

Section: Theorymentioning

confidence: 99%