Tunnel ionization rates; question on atomic units

[dnic12345]

Homework Statement

First of all, this is my first post here, so I apologize if I format things incorrectly.

I'm working on a Matlab script to evaluate the tunnel ionization rates via the PPT model given the correct set of input parameters. The rate equation I am using contains equations 1-11 of A. Talebpour, et al. "Semi-empirical model for the rate of tunnel ionization..." from Opcits Communications 163, (1999) 29-32.

The paragraph leading up to the formula gives "In this model the rate of the TI from a state of an atom with ionization potential Ei, quantum numbers l and m and effective charge Zeff, in a laser field with frequency w and peak electric field F, in atomic units is given by..."

My rate calculations are giving me answers that are many orders of magnitudes off and I think its due to my use of atomic units. I know I have l,m, and Zeff in my equations correct, but I am unsure on the ionization potentials, frequencies, and electric fields in atomic units. The values I have in other units are:

w = 2.8986e+014 Hz (1035 nm wavelength)
Ei = 15.58 eV (N2)
E-field = 1.5e10 V/m

Homework Equations

There are way too many to type out for this formula; my main question is about atomic units. See the above-referenced paper for the actual equations.

The Attempt at a Solution

I've read about atomic units meaning that many constants (like h, hbar, etc) are identically set to 1, but I can't see how to apply this in my situation. I have found several different conversion factors online, but I can't convince myself that any of them are right.

If anyone is familiar with using atomic units in situations like this, please help!

Thanks

 

[nickjer]

Have you looked at this:

http://en.wikipedia.org/wiki/Atomic_units

I do know that Hartree is the atomic unit for energy.

 

[dnic12345]

Yea, I read through that and a number of other pages/pdfs. I did end up using values that are identical to what's on the wikipedia page. I believe I found my problem: the conglomeration of the eqs 1-11 spits out the tunnel ionization rate that I assumed to be in units of Hz. It makes more sense for the TI rate to be atomic units, given that all the inputs are in AU. When I convert the rate I calculate from AU to Hz, I get rates that are much closer to the reference values I have.

Now I think my work is just to make sure I have input and evaluated everything else correctly. I did use an approximation to an infinite sum that may be the key to my error.

Thanks for the response.

 

[nickjer]

No problem, and good luck.

 

[paranormal]

I understand your confusion about using atomic units in your calculations. Atomic units are a system of natural units, where certain fundamental constants are set to 1, making calculations simpler and more elegant. However, it can be challenging to convert values from other units into atomic units, especially if you are not familiar with the conversion factors.

In this case, the first step would be to convert all your values into their corresponding atomic unit equivalents. For example, the frequency can be converted using the formula ω = 2πc/λ, where c is the speed of light and λ is the wavelength. Once you have all your values in atomic units, you can proceed with your calculations using the equations provided in the paper.

It is also important to double-check your equations and make sure they are set up correctly. Sometimes, small mistakes in the equations can lead to significant errors in the results. Additionally, you can try comparing your results with those obtained by other researchers using the same model to check for any discrepancies.

I hope this helps in solving your problem. Good luck with your calculations!