Lennard-Jones Force Formula Python Program

[eximius]

I'm not looking for the answer, I just want some help with understanding the question. The main thing I'm stuck on is the characteristic binding energy and the characteristic molecular size. I've tried searching for these but I'm finding a lot of different stuff.

Homework Statement

All to be done in Python.

Homework Equations

F = (-24*bind)*(((2.0/r)*(sigma/r)**12) -((1.0/r)*(sigma/r)**6))

The Attempt at a Solution

This is what I've done so far. I'm not even sure if the formula function is correct. Because the plot I get begins at a high value fort the Force but falls quickly to zero and remains at zero.

def lgfunc(bind,sigma,r):
    '''
    Function to calculate force between two particles using
    Lennard-Jones formula
    '''
    F = (-24*bind)*(((2.0/r)*(sigma/r)**12) -((1.0/r)*(sigma/r)**6))
    
    return F
  
#For H2 -
  
bind = 4.48*1.6e-19
sigma = 2.92e-10
r = linspace(0,5e-9,50000)

plot(r,lgfunc(bind,sigma,r),'r.')

Any and all help would be greatly appreciated. Thanks

 

[lofgran]

I can provide some clarification on the terms "characteristic binding energy" and "characteristic molecular size" in the context of the Lennard-Jones formula you are working with.

The characteristic binding energy in this formula refers to the minimum energy required to break the bond between two particles. In other words, it is the energy at which the force between the particles becomes zero. In your code, this is represented by the variable "bind," which is multiplied by -24 in the formula.

The characteristic molecular size, on the other hand, refers to the distance at which the force between the particles is zero. In the Lennard-Jones formula, this is represented by the variable "sigma." This value is typically the distance at which the potential energy between the particles is at its minimum.

In terms of understanding the formula itself, it may be helpful to plot it with different values for "bind" and "sigma" to see how they affect the shape of the curve. You can also try plotting the potential energy (rather than the force) to get a better sense of how these variables impact the overall interaction between the particles.

Additionally, I would recommend looking into the units for each variable in the formula to ensure that they are all consistent. This may also help with understanding the behavior of the plot.

I hope this helps! Let me know if you have any other questions or if you need further clarification. Happy coding!