Recent content by wsttiger

You can measure the magnetic structure factor, S(q) using elastic neutron scattering. You then can propose a magnetic structure that will match S(q). It works just like measuring the lattice structure.

I don't know exactly what you're looking for but a lot of the transition metal oxides have a perovskite (either perfect but could be severely distorted) structure. Transition metal oxides are interesting today but many exotic properties such as high-Tc superconductivity, CMR (colossal...

But do the materials that are spin liquids have a normal crystalline lattice structure?

I'm having trouble understanding what you are asking. Fourier transforms are used to transform a real-space function (like an orbital) into momentum space (i.e., change the basis into a plane-wave basis). Once this is done, the |r-r'|^-1 convolution can be performed by dividing by k^2 (where k...

The coulomb integral is diagonal in Fourier space. It's just 1 / k^2 where k is the wavevector.

What's the r-dependence of the orbitals? pz only gives information about the theta and phi dependence.

I don't use either (I use LAPW method), but their both plane-wave / pseudopotential codes. I think that VASP is supposed to have a bit more bells and whistles (which may be of help since you say that you're a newbie). The upside to ESPRESSO (or PWscf) is that it's free. Maybe you would want to...

Within the single-particle approximation, the antibonding orbital is an excited state of the molecule. Furthermore, in the ground state this orbital should be empty. I'm not sure what you're asking in the second question. When you bring multiple atoms together, the Hamiltonian changes and thus...

My simple cartoon way of understanding the fermi level is where nature ran out of electrons. Nature keeps filling energy levels (or energy bands in crystals) until it runs out. So, basically states below the fermi level are occupied ... above the fermi level are unoccupied. In metals it's a...

I think that the book you would be looking for is Fetter and Walecka. Also Mahan's book. Both of these book derive the Dyson equation starting from perturbation theory using the interaction picture.

I was replying to your statement that fortran is the most popular language among "computer scientist"; that is simply not true. However, it probably is the most popular among computational scientists for the reasons that you mentioned above. C is on par with fortran as far as speed goes, but...

corydalus There's no way that the favorite programming language among computer scientists is fortran. It's definitely C or C++. Fortran has only one kind of data structure --- arrays. Computer scientist need many kinds of data structures --- lists, vectors, arrays, hashmaps, red-black trees...

This is a great book, but a little advanced if you don't know quantum mechanics: https://www.amazon.com/dp/0521833469/?tag=pfamazon01-20 Here's another book that a friend of mine has. It's a bit easier. https://www.amazon.com/dp/3527406263/?tag=pfamazon01-20

Maybe try CRYSTAL

It means that on the n-th iteration of the KS loop, the density that you compute from the KS states is equal to the density computed on the (n-1)-th iteration.