Driver Usage

Driver Usage#

Data preparation#

To run the LibRPA driver for RPA/GW calculation, you need to export necessary data from atomic-basis first-principles code. The data include

  • Atomistic structure

  • one-particle orbital energies, occupation numbers and wave functions

  • Bloch vectors used in periodic calculation

  • Triple co-efficients of resolution of identity (RI)

  • Coulomb matrix under the auxiliary basis for RI

FHI-aims#

Export of data required by LibRPA from FHI-aims is supported since the release version 231212 and also in the latest master branch. You can switch it on by adding to your control.in file:

output librpa
# legacy switch before 240507 release
print_librpa_input .true.

It will dump necessary data files for many-body computation tasks. Please refer to the FHI-aims manual for more details of the output librpa tag.

ABACUS#

Similar to the case with FHI-aims, the latest master branch of ABACUS supports the export of files required by LibRPA. You only need to add the following line to the INPUT file of ABACUS:

rpa 1

LibRPA job#

Input file#

Before triggering the LibRPA driver, an input file named librpa.in is required at the working directory. An example is below:

task = rpa
input_dir = .
nfreq = 16
cs_threshold = 1e-4

The driver will read the parameters defined in the file and run the calculation Please refer to the guide page of runtime parameters for more information about the driver and API parameters.

Run the calculation#

After setting up the input file librpa.in, the LibRPA driver can be called by issuing:

/path/to/LibRPA/build/chi0_main.exe

To run with multiple processes using MPI, you can simply invoke the relevant MPI driver, for example

mpirun -np <nprocs> /path/to/LibRPA/build/chi0_main.exe

where <nprocs> is the number of MPI processes. In addition, you want to run with multiple threads, you need to specify the environment variable OMP_NUM_THREADS. For example

export OMP_NUM_THREADS=4
mpirun -np 4 /path/to/LibRPA/build/chi0_main.exe

This will run the LibRPA calculation using 4 MPI processes, each with 4 OpenMP threads.