ABINIT Discussion Forums

Hello, I am working on relaxing some structures for phonon calculations. The first few iterations of the relaxations work as expected (energies and forces decreasing with each step), but eventually, rather the converging, the structures tend to explode and the energy skyrockets. Has anyone experienc...

Dear Ali, You have several definitions of the piezoelectric tensor ( e , d , etc ) with different units and you can select which one you want through the anaddb flag piezoflag ( https://docs.abinit.org/variables/anaddb/#piezoflag ). You can also find some details in the former Phys. Rev. B 72, 0351...

Hello, I'm having some trouble understanding the units Anaddb writes out the piezoelectric tensor with. The piezoelectric tensor should have units of m/V (usually on the order of pm/V), but Anaddb claims the units it's using are C/m^2, which isn't equivalent to m/V. I'm further confused by this rece...

Dear Ali, Abinit is using electronic units by default and the electronic mass is 1836.152... times the proton mass such as if you multiply by this factor you get something close to 1. PS: what do the ; next to Mode 4 indicate? They are different from the - next to Mode 5. I never remarked that, I'l...

Hello, I'm having trouble finding how ABINIT normalizes the phonon eigendisplacements it prints out in doing certain response calculations. My understanding is that for mode m and atom k (dropping indices for direction and wave vector, for simplicity), the phonon eigendisplacement U(m,k) is related ...

Hello, Is it possible to use GW in response calculations? I'm specifically interested in non-linear optical (NLO) properties. From the NLO tutorial, the steps involved in calculating the NLO properties are (1) self-consistent calculation in the IBZ; (2) non self-consistent calculations to get the wa...

Dear Ali, You can indeed restart your calculation without redoing the whole 1, 2, 3 steps. If you have a too big system, mostly if doing NLO, I recommend you to run the different datasets separately and then merge the necessary information. To that end you have to read the wave-functions, ddk and f...

Hello, I am working on a calculating NLO responses in a system with 40 atoms. Following the tutorial on NLO, I have split my calculation into 5 datasets: "(1) self-consistent calculation in the IBZ; (2) non self-consistent calculations to get the wave-functions over the full BZ; (3) ddk calcula...