Interatomic coulombic potential

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The partial charge is the charge of a specific part of a molecule, while the numerical charge is a unit used to measure the charge of particles. In this case, it is used to measure the charge of an electron.
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Hypatio
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I am trying to calculate coulombic potentials. The equation given in wikipedia is

[tex]F=k_e\frac{q_{1}q_{2}}{r^2}[/tex]

where k_e is in units of N m^2 C^-2, q are the partial charges, and r is the distance.

However, I look here and they give k_e=2.31*10^19 and remove the square of the distance. I assume that the difference is related to the units, which is in J*nm in this other resource, but if k_e is a constant then how can an equation of the form 1/r^2 give the same answer as one with the form 1/r?

Also, is the given value of k_e (2.31*10^19 J*nm) very accurate? What is the more accurate value?
 
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  • #2
Hi Hypatio! :smile:

(try using the X2 button just above the Reply box :wink:)
Hypatio said:
I am trying to calculate coulombic potentials.

However, I look here and they give k_e=2.31*1019 and remove the square of the distance. I assume that the difference is related to the units, which is in J*nm in this other resource, but if k_e is a constant then how can an equation of the form 1/r2give the same answer as one with the form 1/r?

the force is ~ 1/r2

the potential is ~ 1/r :wink:
Also, is the given value of k_e (2.31*1019 J*nm) very accurate? What is the more accurate value?

i don't recognise that figure

the usual constant in Coulomb's law is 8.988 x 109 N m2/C2

(or 8.987 551 787 368 176 4, see http://en.wikipedia.org/wiki/Coulomb's_law#The_law)
 
  • #3
Hypatio said:
I am trying to calculate coulombic potentials. The equation given in wikipedia is

[tex]F=k_e\frac{q_{1}q_{2}}{r^2}[/tex]

where k_e is in units of N m^2 C^-2, q are the partial charges, and r is the distance.

However, I look here and they give k_e=2.31*10^19 and remove the square of the distance. I assume that the difference is related to the units, which is in J*nm in this other resource, but if k_e is a constant then how can an equation of the form 1/r^2 give the same answer as one with the form 1/r?

Also, is the given value of k_e (2.31*10^19 J*nm) very accurate? What is the more accurate value?

The formula in the paper is for energy and not for force:
[tex]E=k_e\frac{q_{1}q_{2}}{r}[/tex]
The numerical constant comes from the units: they use the numerical charge (number of electron charges) and not the charge in coulombs.
They also use the distance in nm.
So the number you see is

[tex]k_e\times e^2\times 10^9[/tex]
 
  • #4
Thanks!

What is the difference between the partial charge and the 'numerical charge'? Also, what is the parameter e?
 
  • #5
Numerical charge is the charge in units of elementary (electron charge).
e is the value of the elementary charge (1.6x10^(-19) C).
 

1. What is interatomic coulombic potential?

Interatomic coulombic potential is a mathematical representation of the interaction between two or more charged atoms or molecules. It describes the electrostatic force between these particles and is an important factor in determining the overall stability and behavior of a material.

2. How is interatomic coulombic potential calculated?

Interatomic coulombic potential is calculated using Coulomb's law, which states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. This calculation takes into account the charges and distances of all particles involved.

3. What factors affect interatomic coulombic potential?

The magnitude of interatomic coulombic potential is influenced by the charges of the atoms or molecules involved, as well as their relative positions. Additionally, the dielectric constant of the surrounding medium and the presence of any screening charges can also affect the strength of the potential.

4. How does interatomic coulombic potential impact material properties?

Interatomic coulombic potential plays a crucial role in determining the structural and electronic properties of materials. It affects the bond strength between atoms, the lattice structure of solids, and the overall behavior of a material under different conditions such as temperature and pressure.

5. Can interatomic coulombic potential be manipulated?

Interatomic coulombic potential can be modified by altering the charges or distances of the particles involved, as well as by changing the surrounding environment. This can be achieved through various methods such as doping, applying external electric fields, or introducing defects in the material.

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