Printing the eignenvectors and values after a run has finished

CaesarSalad

Hello,

Is there a way to print the eigenvectors and eigenvalues of a system after a simulation has finished running?

Chris

eascrizzi

Hi Chris!

You can perform a NEWK properties calculation (see page 346 of CRYSTAL User's Manual) starting from your converged wavefunction and select the printing options for eigenvalues and eigenvectors.

Hope this answers your question

Eleonora

CaesarSalad

Hi Eleonora,

Thanks for your reply. So the calculation can simply be ran as:

NEWK
6 6
1 66 67

? Or do I have to run two separate calculations, one with "1 66" and one with "1 67" on the second line?

Chris

GiacomoAmbrogio

Hi Chris,

If you want to switch on printing options 66 and 67, your input should be:

NEWK
6 6
1 2
66 xxx
67 yyy

where xxx and yyy are the numbers "N" specified in the manual (see page 443, column input)

Let me know if you manage to get the correct printings

CaesarSalad

Hi Giacomo,

Thanks for the input. It seems that this would only print the eigenvalues. The eigenvectors won't be printed and I get this error at the end of the output file:

FERMI ENERGY AND DENSITY MATRIX CALCULATION ON COMPUTED EIGENVECTORS
DENSITY MATRIX AT SCF CYCLE ( 3+1)
SPIN LOCKING: NO ENERGY GAP COMPUTED
CORE DENSITY MATRIX CALCULATION
TTTTTTTTTTTTTTTTTTTTTTTTTTTTTT NEWK TELAPSE 16.38 TCPU 14.78
ERROR **** properties **** END OF DATA IN INPUT DECK

My input is:

NEWK
6 6
1 2
66 -505
67 -505

..ran via crystal_properties binaries. Could it be because 67 works only by printing at the end of the SCF cycles?

Chris

GiacomoAmbrogio

Hi Chris,

The error comes from the missing END line that should close the NEWK block.

As for print option 67: it should work in properties as well as in crystal. That said, these print flags are not very well tested, and some of them may have broken in newer versions. I took a look in the code, and I can confirm that the -505 trick will not work here. Instead, you should set the value to 999 to get the maximum possible output (ie all the virtual states, or 499 for just the occupied states).

One more note: in the NEWK section this option was never extended to parallel execution, so you’ll need to run it on a single CPU core if you want it to print.

Hope this helps.

CaesarSalad

Hi Giacomo,

Sorry for the late reply. I can confirm that 999 works in this scenario even using parallel execution settings. I tried to pass the HPC the command to run the simulation on a single CPU core but it kept complaining that it is not set up to do so, so I ran it on multiple CPUs and it worked. However, it is printing the eigenvectors for K points 48 and 80. Is there a way to print the eigenvectors at the Gamma point only? Additionally, when I try:

NEWK
4 4
1 2
66 -505
67 999
END

It will not print the eigenvectors (just the eigenvalues), even though the initial crystal run for calculating the ground-state via DFT was ran with SHRINK 4 4. There is no error at the end of the output file, it just ends. I'm not sure why, to be honest, but maybe it's got something to do with the number of CPUs this is running on? I might try to run it with less than 80 CPU cores (which is the standard number I use for Crystal simulations) and see what happens. In the meantime if you have any insight I would greatly appreciate it,

Thanks in advance for your help,

Chris

GiacomoAmbrogio

Hi Chris,

The reason you only see a few k-points printed is indeed that the printing options are not fully supported in parallel execution. In a parallel run, each MPI process handles a subset of the k-points, and only process 0 writes to the output file. As a result, you’ll only see the k-points assigned to process 0, which can be just a few, or even none, depending on how they are distributed.

By default, the code distributes k-points in a round-robin fashion starting from the last process, so the gamma point is typically assigned to the last process and therefore never printed in a parallel execution.

This behavior applies to both options 66 and 67.

Try running the following input:

NEWK
4 4
1 2
66 999
67 999
END

However, you’ll need to run it on a single process for the eigenvectors to be printed correctly.

If the calculation is too expensive to run on a single process, we may need to find an alternative approach to extract those values (though that won’t be straightforward).