NEB replicas?

[Ernst Larsson]

Dear all,

I'm slightly confused about the "NUMBER_OF_REPLICA" keyword when performing a NEB-calculations.

I've optimized the start and end points separately, which due to symmetry have the same energies.

When I run the NEB-calculation, I provide three intermediate starting guesses which I've interpolated myself (I know that CP2K in principle can do this for me) and set "NUMBER_OF_REPLICA = 5".

My confusion comes when I look at the energies and files:

1) I get six files of the type '...-BANDX.out' rather than five.

2) The ENERGIES section in the NEB-output give me five energies, which is fine, but only the start point matches what I got from the geometry optimisation. The last replica has an energy which is larger than what it should be by 0.011205 a.u., (when it should be identical to the first). If I check "...-pos-Replica_nr_5-1.xyz" which I presume is for the endpoint, it is not identical to what I specified as my end point in the input.

3) The energy in this extra '...-BANDX.out'-file does not match the correct end-point either.

Does anyone have any good idea on what may be going wrong?

I've attached my NEB-input script.

Regards,

Ernst

[fabia...@gmail.com]

Hi Ernst,

You can set ALIGN_FRAMES and  ROTATE_FRAME to .FALSE. to prevent this behavior.

Cheers,

Fabian

[Ernst Larsson]

Dear Fabia,

Thank you very much!

The additional keywords seem to have solve the energy issues.

I still get one extra ’…-BANDX.out”-file though….

Regards,

Ernst

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[Marcella Iannuzzi]

Dear Ernst, 

The extra output file should be due to the ratio between the the total number of tasks and the number of tasks per replica, 

which I suspect does not correspond to the number of replicas. 

Best

Marcella