RT-TDDFT cannot read wave functions to restart simulations

[1041176461]

Describe the bug

When running RT-TDDFT with md_restart 1 and init_wfc file for restarting a job, a warning is reported

However, there are wfc files with different names under OUT* directory:

[pxlxingliang]

The wfc file in OUT* directory is from the job with out_app_flag = false, which will generate some WFC files with filename containing ION step information. Now, ABACUS do not support init_wfc from the files generated with out_app_flag = false, because ABACUS do not know which ION step should be read. To support this case, we need to add an INPUT parameter to let ABACUS know the ION step of WFC file.

[1041176461]

As far as I know, TDDFT needs to read the time-evolved wave function to restart the task. I don't know how it is implemented in the program, but reading an append file is definitely unrealistic. Maybe @AsTonyshment and @lyb9812 are more familiar with it.

[AsTonyshment]

@1041176461 In my impression, for TDDFT calculations, if a job restart is needed, you should set out_wfc_lcao=1 during the calculation, and then you can continue the calculation by setting md_restart=1. There should be no need to set the init_wfc parameter. However, as far as I know, there seem to be some issues with reading in the electric field during restart. It might be necessary to reset the electric field from the restart point, otherwise the efield_*.dat file might encounter problems. This was my experience from using it three months ago, so I'm not sure if the restart logic has been updated since then...

[1041176461]

1. I also did not set the restart with init_wfc turned on before, but the last step before the restart and the first step after the restart had inconsistent self-consistent energy. I turned off the electric field when restarting here because the electric field had ended before the restart
   RT-TDDFT detects memory leak #4617 (comment)

2. If init_wfc does not need to be set, why do we need to set out_wfc_lcao? Will md_restart read the wave function?

3. out_wfc_lcao=1 with out_app_flag = 0 will generate a huge file for md, I think reading this file will become very slow

[AsTonyshment]

The restart logic was written by @lyb9812. Maybe you can explain about this?

[lyb9812]

1. I also did not set the restart with init_wfc turned on before, but the last step before the restart and the first step after the restart had inconsistent self-consistent energy. I turned off the electric field when restarting here because the electric field had ended before the restart
   RT-TDDFT abnormally interrupted #4617 (comment)
2. If init_wfc does not need to be set, why do we need to set out_wfc_lcao? Will md_restart read the wave function?
3. out_wfc_lcao=1 with out_app_flag = 0 will generate a huge file for md, I think reading this file will become very slow

Both init_wfc and md_restart need to be set. You can set out_interval to reduce the output. The velocity gauge may not support the restart function. It hasn't been tested yet.

[mohanchen]

It's not a good idea to print out the wave functions at each TDDFT step, the files will be too large.