[CP2K-user] [CP2K:21270] Question about REFTRAJ

[fengming shi]

Dear CP2K Developers,

I am using REFTRAJ to compute the energy, forces, and stress for a 
trajectory of 100 structures sampled from a classical molecular dynamics 
simulation to build a training dataset. To validate the results, I compared 
the REFTRAJ outputs with those obtained from separate calculations on the 
first four structures. While the results are generally consistent, I 
noticed some small differences.

For the first structure, the total energy differs at the 10th decimal 
place, the forces and stress are identical. These discrepancies increase 
slightly for subsequent structures. After examining the outputs from 
REFTRAJ and the separate calculations, I found that the energy differences 
from the second structure onward stem from variations in the Core 
Hamiltonian energy, Hartree energy, and exchange-correlation energy.

I would like to understand what causes these differences and whether they 
are expected. Both methods use the same *FORCE_EVAL* settings, with 
*SCF/SCF_GUESS* set to ATOMIC and *QS/EXTRAPOLATION* set to USE_GUESS. The 
input scripts and output files are attached for your reference. 

Although these differences are too small to impact the quality of my 
training dataset, I am curious about the underlying reasons. I would 
appreciate any insights you can provide.

Thank you in advance for your time and help!

Best regards,

Fengming Shi

[image: REFTRAJ_SP_results.png]

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cp2k/75867a5d-8eb1-431c-9f07-27639952a556n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: trj_0B.extxyz
Type: application/octet-stream
Size: 59312 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0004.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: REFTRAJ.out
Type: application/octet-stream
Size: 502285 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0005.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SP.inp
Type: chemical/x-gamess-input
Size: 2233 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0002.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: vol_0B.cell
Type: application/octet-stream
Size: 895 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0006.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: REFTRAJ.inp
Type: chemical/x-gamess-input
Size: 2540 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0003.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SP_structure2.out
Type: application/octet-stream
Size: 241219 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0007.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: REFTRAJ_SP_results.png
Type: image/png
Size: 60776 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250307/124e889c/attachment-0001.png>