TiO2 hybrid functionals parallelism

Running Abinit Ground state
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1

Dear Abinit community I have been running into an issue in using parallelism and hybrid functional calculations. I have attached the .abi file that I am currently using. I have read the wiki about using hybrid functionals and have some questions about them.

1.MPIRUN vs. openmp, I can ran the system it constantly gives errors that after my calculation it stops suddenly, I don’t have the exact error message, I accidentally overwrote it but it stated the mpi IO does not work for hybrid functionals, due to a format error of the wave function. Does this mean that it is impossible to use parallelism over anything other than k points? Also how does one enable only openmp instead of mpi, when, using hybrid functionals? The one error when switching io mode to zero is

“— !WARNING
src_file: Subroutine Unknown
src_line: 0
message: |
When k-points/bands/FFT parallelism is activated
(paral_kgb=1), only MPI-IO input/output is allowed !
iomode/=1 in your input file
You will not be able to perform input/output !”

2.Hybrid functionals calculations require two data set a non hybrid run and the second hybrid run using the previous wave function from the first calculation is it possible to import a converged wave function file first and then run the hybrid functionals

Please let me know if you need any more information.

TiO2hybrid.txt (4.2 KB)

2

Hi Christopher,

I am a simple user for that part of ABINIT. So apologize my partial answers.

  1. When running hybrid functionals, you can use nphf keyword that divides the occupied states in exchange operator among the MPI processors. It usually parallelizes more efficiently than the other strategies.
    I am not using OPENMP. In general, I find it not efficient at all.

  2. Hybrid functionals do not require two data sets. You may use only one.
    However it is a clever strategy to first do a fast PBE calculation and then start-up the hybrid functional from the PBE wavefunction file.
    I usually read the WFK file from a previous run with keyword
    ```
    getwfk_filepath1 "diamond_pbe_WFK"
    ```
    Let us know if it helps.
    Best

Fabien