# Recent content by SpinFlop

1. ### MATLAB Extract elements from a cell

For future reference, when performing a uniform operation on arrays inside of a cell, just write a function to perform your desired task and have it operate across the cell using cellfun. For your current problem it would look like this: cellfun(@(f)f(1,2), a)
2. ### I Why are there not more ferromagnetic Materials?

To begin, your quote from an unnamed source speaks of the "spherical symmetry of the environment" which you then took upon yourself to recast as "spherical movement of an electron" (a statement that is problematic in and of itself, but one that I am not going to address.) If we focus on what the...
3. ### A Electronic band structure of iron superconductor BaFe2As2

As general rule, it is not very reasonable to expect that atoms, when condensed into a material, will follow a simple Hund's filling. Here is an article on the 122 pnictides that includes both theory and experiment that demonstrate the important role of correlations in establishing the...
4. ### I Molecular vibrations

When atoms condense into a solid, then, as TeethWhitener pointed out, the primary modes are acoustic and optical phonons. These are vibrations that move as a wave through the material, ie: they are collective modes due to long range coordination of the atoms. In fact, they are guaranteed to...
5. ### Transmission of a thin film fitting using the Swanepoel method in MATLAB isn't working

They clearly have a typo in their definition of C since there are two opening parenthesis, but only one closing. My guess is that it should be $2(n^2 - 1)(n^2 - s^2)$. Try that and see if it fixes the problem.
6. ### A What is the mean inner potential in an ideal crystal of finite size?

As I stated above, the paper I recommended works out the potential for you cubic system in the first half. The second half then works out the energy level scheme due to splitting the orbital degeneracy of electrons placed within this crystal field. So there is no simpler model, just disregard...
7. ### A What is the mean inner potential in an ideal crystal of finite size?

What you are describing is Crystal Field Theory. There is extensive literature on this and the associated energy splitting of electron orbital degeneracy within these crystalline electric fields, ie: CEF levels. In general, the number of levels is determined by the local point group symmetry of...

13. ### I Taylor Series for Potential in Crystals

The answer as to why we do a Taylor expansion at all is because physics is hard. Indeed, for the Lennard Jones potential we use to describe lattice dynamics exact solutions are altogether intractable. So we do what we typically do with potentials in such cases, we Taylor expand around the...