II.—The Van der Waals Force between a Proton and a Hydrogen Atom

Author(s):  
C. A. Coulson

The calculation of Van der Waals forces has acquired considerable interest recently through the work of Buckingham, Knipp and others (Buckingham, 1937; Knipp, 1939). In these papers the interaction energy between two atoms is expressed as a power series in i/R, where R is the nuclear separation, and the various terms in this series are known as dipole-dipole, dipole-quadrupole, quadrupole-quadrupole, etc… interactions. In most cases only approximate values are obtainable for the coefficients in this series, though for two hydrogen atoms in their ground states, Pauling and Beach (1935) have determined the magnitudes correct to about I in 106. In this paper we discuss the simplest possible problem of this nature, i.e. the force between a bare proton and a normal unexcited hydrogen atom. We shall show that a rigorous determination of the coefficients in the power series can be made.

Author(s):  
C. A. Coulson ◽  
C. M. Gillam

SummaryThe interaction energy, or Van der Waals force, between a proton and a hydrogen atom in any one of its allowed quantum states is calculated in terms of the internuclear distance R by an expansion of the formAll the coefficients up to and including E5 are obtained in closed form. For values of R for which the expansion is valid, the coefficients are determined absolutely, no approximations being introduced.


2011 ◽  
Vol 03 ◽  
pp. 555-563 ◽  
Author(s):  
YU. V. CHURKIN ◽  
A. B. FEDORTSOV ◽  
G. L. KLIMCHITSKAYA ◽  
V. A. YUROVA

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.


1973 ◽  
Vol 51 (3) ◽  
pp. 370-372 ◽  
Author(s):  
R. Atkinson ◽  
R. J. Cvetanović

A modulation technique has been used to determine from phase shift measurements the absolute values of the rate constants and the Arrhenius parameters of the reaction of hydrogen atoms with nitric oxide.


2011 ◽  
Vol 26 (22) ◽  
pp. 3958-3966 ◽  
Author(s):  
YU. V. CHURKIN ◽  
A. B. FEDORTSOV ◽  
G. L. KLIMCHITSKAYA ◽  
V. A. YUROVA

We calculate the interaction energy and force between atoms and molecules and single-walled carbon nanotubes described by the Dirac model of graphene. For this purpose the Lifshitz-type formulas adapted for the case of cylindrical geometry with the help of the proximity force approximation are used. The results obtained are compared with those derived from the hydrodymanic model of graphene. Numerical computations are performed for hydrogen atoms and molecules. It is shown that the Dirac model leads to larger values of the van der Waals force than the hydrodynamic model. For a hydrogen molecule the interaction energy and force computed using both models are larger than for a hydrogen atom.


Nature ◽  
1936 ◽  
Vol 138 (3480) ◽  
pp. 77-77 ◽  
Author(s):  
H. S. W. MASSEY ◽  
R. A. BUCKINGHAM

The crystal structure of ammonium oxamate (CONH 2 .COONH 4 ) has been studied using Cu Ka X-radiation, by means of a three-circle diffractometer incorporating a xenon-filled proportional counter. Accurate three-dimensional intensity data were collected and a least-squares refinement was carried out. The positions of the hydrogen atoms were obtained and refined. A peak of electron density, about half as high as a hydrogen atom, was observed at the centre of the C—C bond and a correction applied for it increased the length of the bond by 0.003 Å. The bond lengths were corrected for librational motion, and the values obtained are C—C =1.564 ±0.002 Å; C—N = 1.324± 0.002 Å; C—O (amidic) = 1.248± 0.002 A; C— O (carboxylate) = 1.257 + 0.003 Å and 1.256 ± 0.003 Å. The oxamate ion is found to be planar, and the ammonium ion tetrahedral. The length of the C—C bond is greater than any theoretical value yet suggested for the length of a single bond between trigonally hybridized carbons atoms.


Sign in / Sign up

Export Citation Format

Share Document