loss of the Core-shell bond during thermalisation

Dear Lammps users,

I am getting some problems when trying to use the implementation of the core-shell model of Mitchell and Finchham in order to perform calculations on zinc sulfide.

I use a Coulomb-Buckingham potential combined with the core-shell option and LAMMPS version of august 10th 2015

I created my crystal and performed a minimization but when I initialize the temperature of the system in order to perform a NVE and NPT thermalisation, I lose the bond between core and shell (ERROR on proc: Bond atoms 1 385 missing on proc 0 at step 157 (…/neigh_bond.cpp:65)) .

The only solution I found is to put a very small timestep (2.10^-10 ps).

But this solution will dramatically impact the computational time since my final objective is to determine diffusion coefficient by MSD calculation at different temperatures.

Does someone have a better idea to solve this problem or any explanation about the origin of the non-sense forces causing the bonds to disappear?

You will find enclosed the input files (in.ZnX3, pot.mod and init.mod) and the output file (error_code).

I hope one of you can help me.

Thank you in advance

Best regards.

Kévin Perrin
Ph. D. Student

IFP Energies nouvelles – Direction Catalyse et Séparation
Etablissement de Lyon
Rond-point de l’échangeur de Solaize - BP 3
69360 Solaize - France
Tél. : 04 37 70 31 91
[email protected]…2875…

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www.ifpenergiesnouvelles.fr

error_code (8.33 KB)

in.ZnX3 (4.48 KB)

init.mod (970 Bytes)

pot.mod (1.87 KB)

Did you read Section 6.26 of the manual and successfully

run the examples/coreshell script? Are yiou using compute temp/cs

and the temp init strategy in examples/coreshell?

I would try the current version of LAMMPS (may have been

some bug fixes in last year), and if that all fails, send

an email to Hendrik.

Steve

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Dear Steve,

Thank you for your advice and prompt answer.

I just found a solution, I did not pay attention on the shell weight and I put a value near to zero. When I increase the shell weight (1-2 % of the atom weight), The calculation runs with a reasonable timestep .

Moreover this change seems not to impact diffusion coefficient calculation according to Mitchell and Fincham (http://dx.doi.org/10.1088/0953-8984/5/8/006).

Best regards,

Kévin Perrin
Doctorant

IFP Energies nouvelles – Direction Catalyse et Séparation
Etablissement de Lyon
Rond-point de l’échangeur de Solaize - BP 3
69360 Solaize - France
Tél. : 04 37 70 31 91
[email protected]…2875…

image001.gif
www.ifpenergiesnouvelles.fr

Envoyé : mercredi 26 octobre 2016 16:27

Dear Steve,

Thank you for your advice and prompt answer.

I just found a solution, I did not pay attention on the shell weight and I
put a value near to zero. When I increase the shell weight (1-2 % of the
atom weight), The calculation runs with a reasonable timestep .

Moreover this change seems not to impact diffusion coefficient calculation
according to Mitchell and Fincham (http://dx.doi.org/10.1088/
0953-8984/5/8/006).

​kevin,

is this information properly conveyed in the documentation? if not, please
suggest changes or additions.

thanks,
    axel.​

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