Hello, aerba!
The method you proposed actually worked. Thank you very much for your help in resolving this issue.

Hello, aerba!
Thank you very much for the reply! We are indeed using an older version of the program, CRYSTAL17, as we officially purchased it. Unfortunately, despite our strong desire to obtain the newer version, it is currently beyond my capacity to implement this upgrade.

The calculation you sent is very important to us, as it represents the final point for studying the dynamics in our series. Because of this, we are a bit at a loss as to whether it can be used in a future publication. Therefore, we would like to know if there is any possibility to run the ELASTCON calculation using the older version of the software.

Hello!
I'm having trouble calculating the elastic tensor using the ELASTCON keyword.
Every time, the calculation stops at STRAIN MATRIX 3
The structure's geometry has been pre-optimized.
Could you tell me what the problem might be and if it can be fixed?
INPUT.d12
fort34.txt
fort87.txt

aerba, Thank you very much for your reply!

Unfortunately, I don't speak English very well, which is why I may have phrased my question incorrectly.

My question was that the function OPTGEOM does not work correctly with RUNCONFS. I had already tried the steps you suggested.

However, I was able to figure out the problem. For geometric optimization, I just needed to specify the keyword more correctly:

CRYSTAL 
0 0 0 
194 
3.065 17.656
4
22    0        0        0.5
14    0        0        0.75
22    0.666666 0.333333 0.364919
6     0.333333 0.666666 0.427507
SCELCONF
1 0 0
0 1 0
0 0 1
RUNCONFS
ATOMSUBS
22 273
OPTGEOM
MAXCYCLE
500
ENDOPT
END
END

I'll leave it here, maybe it will be useful to someone in the future.

Nevertheless, thank you very much for your responsiveness

Hello!
Help with the problem! When you try to run geometry optimization for configurations, only the geometry optimization of the original connection is started. I am attaching a view of a part of the input file, as it is all set.

CRYSTAL
0 0 0
194
3.065 17.656
4
22    0        0        0.5
14    0        0        0.75
22    0.666666 0.333333 0.364919
6     0.333333 0.666666 0.427507
SCELCONF
1 0 0
0 1 0
0 0 1
RUNCONFS
ATOMSUBS
22 273
END
OPTGEOM
MAXCYCLE
500
END
END

Thank you!

Hello!
In many articles where CRYSTAL is used, I have come across the following phrase

The energy optimization of the basis sets was undertaken using the Billy software.

which is accompanied by a link to the manual. But there is no information about it in the manual or anywhere else. Can anyone explain what it is? Thank you in advance!