Appearance of long-range interatomic forces in molecular potential curves

2009 ◽  
Vol 4 (S3B) ◽  
pp. 615-616
Author(s):  
J. I. Steinfeld
Keyword(s):  
Long Range ◽  
Molecular Potential ◽  
Potential Curves

scholarly journals Anisotropy Parameters and Adiabatic Approximations for Two-electron Atoms and lons

1990 ◽  
Vol 43 (5) ◽  
pp. 641 ◽  
Author(s):  
Joseph Macek
Keyword(s):  
A Priori ◽  
Dynamical Evolution ◽  
Low Energy ◽  
Asymptotic Region ◽  
Atomic Systems ◽  
Atom Scattering ◽  
Molecular Potential ◽  
Adiabatic Approach ◽  
Anisotropy Parameters ◽  
Potential Curves

In dynamial processes atomic systems evolve from a condensation region at small distances where all particles are close together to an asymptotic region where some of the constituent particles are free and accessible to measurement. This dynamical evolution is characterised by the Jost matrix. Evaluation of the Jost matrix generally involves complex calculations, but considerable simplification is achieved when the evolution can be described in terms of adiabatic or diabatic potential curves. For low energy ion-atom and atom-atom collisions standard molecular potential curves have long been used. For low energy electron-atom scattering and photo-ionisation similar molecular-like potential curves have been proposed. There is no a priori justification for the adiabatic approach in these latter systems, thus confrontation with experiment is crucial for further development of this theory. Anisotropy parameters represent a particularly appropriate probe of the various adiabatic representations. This is illustrated by studies of photo-ionisation of helium at the n = 2 threshold. Potential curve crossings are important here and their relevance to the anisotropy parameters is illustrated

On the Determination of Molecular Potential Curves from Spectroscopic Data

1938 ◽  
Vol 54 (9) ◽  
pp. 726-738 ◽  
Author(s):  
Albert Sprague Coolidge ◽  
Hubert M. James ◽  
E. L. Vernon
Keyword(s):  
Spectroscopic Data ◽  
Molecular Potential ◽  
Potential Curves

Structures in the long range potential curves of the Na2molecule: comparison between ab initio and asymptotic calculations

1994 ◽  
Vol 27 (9) ◽  
pp. 1723-1741 ◽  
Author(s):  
S Magnier ◽  
M Aubert-Frecon ◽  
O Bouty ◽  
F Masnou-Seeuws ◽  
P Millie ◽  
...  
Keyword(s):  
Ab Initio ◽  
Long Range ◽  
Range Potential ◽  
Potential Curves

Enhanced Long-Range Si···N Interactions in Organosilicon Cations. A Theoretical Study

2001 ◽  
Vol 66 (3) ◽  
pp. 473-482 ◽  
Author(s):  
Zdeněk Havlas ◽  
Hans Bock
Keyword(s):  
Long Range ◽  
Density Functional ◽  
Considerable Increase ◽  
Crystalline Solid ◽  
Cluster Approach ◽  
Functional Theory ◽  
B3lyp Level ◽  
Highly Correlated ◽  
Chemical Procedure ◽  
Potential Curves

For the model organosilicon cation H3N···SiH3+, potential curves have been calculated by density functional theory at the B3LYP level, by both MP2 and MP4 perturbation procedures and by a Coupled Cluster approach. Relative to the analogous potential curve for the uncharged adduct, H3N···SiH4, a considerable increase of the long-range Si···N interaction accompanied by bond shortening is predicted. For chemical comparison, the structure of the "double R2N-twister" dication salt, [C6H4(CH2NR2)2-Si-(R2NCH2)2C6H4]++Cl2-, reported in the literature as a non-crystalline solid, was optimized by DFT calculations and a minimum for the hexacoordinated organosilicon center with each two Si···N bonds of different lengths was located. To test the reliability of the quantum chemical procedure, in addition the analogous and structurally characterized dication salt, [(3-picoline)4SiH2]++[Cl-···(HCCl3)2]2, which contains a hexacoordinated Si center with 4 equivalent Si···N interactions, has been selected to reproduce its structure by DFT optimization. Both hexacoordinated, tetra-N-surrounded Si dications, substantiate the increase of long-range Si···N interactions as predicted by the potential curves for the model adduct H3N···SiH3+ based on highly correlated calculations.

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