# Phonon Density of States (PDOS) at Gamma Point

• RaquelYR
In summary, the conversation discusses the process of replicating phonon density of states (PHDOS) diagrams for solids using Quantum Espresso. The usual procedure involves conducting an scf calculation at minima, calculating the dynamical matrix in reciprocal space, determining interatomic force constants in real space, and calculating phonon frequency. However, there is a difference in the frequencies obtained compared to an example, and it is suggested to calculate at the gamma point. The person seeking help is asking for advice on how to obtain the phonon density of states at the gamma point. In response, it is explained that it is not possible to calculate a density of states at a single point in the Brillouin zone and a tutorial is recommended as a resource

#### RaquelYR

Hello everyone!

I'm trying to replicate phonon density of states (PHDOS) diagrams for some solids using Quantum Espresso. The usual way I do it is the following one:

1. scf calculation at minima (pw.x)
2. Calculation of dynamical matrix in reciprocal space with nq=1 or 2 (ph.x)
3. Calculation of interatomic force constants in real space (q2r.c)
4. Calculation of phonon frequency (matdyn.x)
The frequencies I obtained differ with the ones of the example. The only significant difference that I find is that they perform the calculation at Gamma Point. I have tried to carry out my procedure at gamma point but it seems to be incompatible.

Does any one know how can I get the phonon density of states at gamma point?

It makes no sense to calculate a density of states at the gamma point. The gamma point is only a single point in the Brillouin zone, whereas a density of states gives you the number of states across the entire Brillouin zone with energies between ##E## and ##E+dE##. Regardless, here’s a tutorial for getting a phonon DOS specifically (this person has a whole series of tutorials for Quantum Espresso that are quite good):

gentzen, raisins and Lord Jestocost