Can DFT and ab initio methods adequately describe binding energies in strongly interacting C 6 X 6 ⋯C 2 X n π–π complexes?

2017 ◽  
Vol 493 ◽  
pp. 12-19 ◽  
Author(s):  
Berthelot Saïd Duvalier Ramlina Vamhindi ◽  
Amir Karton
Keyword(s):  
Ab Initio ◽  
Binding Energies ◽  
Ab Initio Methods ◽  
Strongly Interacting

scholarly journals Complexes Between Adamantane Analogues B4X6 -X = {CH2, NH, O ; SiH2, PH, S} - and Dihydrogen, B4X6:nH2 (n = 1–4)

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1042 ◽  
Author(s):  
Josep M. Oliva-Enrich ◽  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Perturbation Theory ◽  
Ab Initio ◽  
Boron Atom ◽  
Electrostatic Potentials ◽  
Binding Energies ◽  
The Other ◽  
Ab Initio Methods ◽  
Molecular Electrostatic Potentials ◽  
Optimized Geometries

In this work, we study the interactions between adamantane-like structures B4X6 with X = {CH2, NH, O ; SiH2, PH, S} and dihydrogen molecules above the Boron atom, with ab initio methods based on perturbation theory (MP2/aug-cc-pVDZ). Molecular electrostatic potentials (MESP) for optimized B4X6 systems, optimized geometries, and binding energies are reported for all B4X6:nH2 (n = 1–4) complexes. All B4X6:nH2 (n = 1–4) complexes show attractive patterns, with B4O6:nH2 systems showing remarkable behavior with larger binding energies and smaller B···H2 distances as compared to the other structures with different X.

scholarly journals Ab initio studies on complexes formed by melamine and cyclotrione

2007 ◽  
Vol 72 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Liangiang Zhu ◽  
Qiwen Teng ◽  
Shi Wu
Keyword(s):  
Ir Spectra ◽  
Ab Initio ◽  
Electronic Properties ◽  
Electronic Spectra ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Basis Sets ◽  
Ab Initio Methods ◽  
Ir And Raman

Ab initio methods were used to study the binding energies of non-bonded complexes formed by melamine and cyclotrione, with the STO-3G, 3-21G and 6-31G (d) basis sets. The electronic spectra were computed using the INDO/CIS method, and the IR spectra, Raman and NMR spectra with the RHF/6-31G (d)method. It was demonstrated that the complexes could be formed because of the negative binding energies, which were changed with the change in the electronic properties of the monomers. A red-shift of the first absorptions in the electronic spectra and the vibrational frequencies of the N-H bonds in the IR and Raman spectra of the complexes, compared with those of the monomers, occurred; simultaneously, the 1Hand 13C chemical shifts were altered, due to the non-bonded interaction. .

Determination of acidic dissociation constants of L-phenylalanyl-glycine and L-alanyl-L-alanine in water using ab initio methods

2014 ◽  
Vol 2 (42) ◽  
pp. 263-263
Author(s):  
Farhoush Kiani ◽  
Mahmoud Tajbakhsh ◽  
Fereydoon Ashrafi ◽  
Nesa Shafiei ◽  
Azar Bahadori ◽  
...  
Keyword(s):  
Ab Initio ◽  
Dissociation Constants ◽  
Ab Initio Methods ◽  
Acidic Dissociation

A pairwise additivity scheme for conformational energies of substituted ethanes

1975 ◽  
Vol 343 (1632) ◽  
pp. 1-10 ◽  
Keyword(s):  
Large Deviations ◽  
Ab Initio ◽  
Dihedral Angle ◽  
Molecular Orbital ◽  
Methyl Groups ◽  
Molecular Orbital Calculations ◽  
Linear Combinations ◽  
Strongly Interacting ◽  
Conformational Energies

Ab initio molecular orbital calculations are used to explore additivity in the conformational energies of poly-substituted ethanes in terms of conformational energies of ethane and appropriate mono- and 1,2-di-substituted derivatives. Such relations would allow complex calculations for poly-substituted ethanes to be replaced by much simpler ones on a small number of parent molecules. General expressions for the linear combinations are derived from the assumption that interactions between vicinal substituents are pairwise additive and depend only on the vicinal dihedral angle. The additivity scheme is tested for 15 ethanes, di-, tri- or tetrasubstituted by cyano and methyl groups and for a smaller number of fluoroethanes. Additivity applies to within 0.1- 0.3 k J mol -1 in the methylethanes and mostly to within about 0.7- 0.8 kJ mol -1 in cyanoethanes. Large deviations are found among the geminally substituted fluoroethanes. It is suggested that the additivity approximation is most successful in the absence of strongly interacting geminal groups. Predictions are made of conformational energies of ten hexa(cyano- and methyl-) substituted ethanes.

Study of the structure and stability of aqua ions La(H2O) n 3+ (n = 8, 9) by ab initio methods

2008 ◽  
Vol 53 (8) ◽  
pp. 1249-1255 ◽  
Author(s):  
V. Yu. Buz’ko ◽  
I. V. Sukhno ◽  
M. B. Buz’ko ◽  
A. A. Polushin ◽  
V. T. Panyushkin
Keyword(s):  
Ab Initio ◽  
Ab Initio Methods ◽  
Structure And Stability
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