Simulation of Si3N4

Hi Prof. Kohlmeyer,

I got your point and my apology for failing to elaborate appropriately on the problem. For potential, I used tersoff potential which was calibrated by Brito Mota. For the initial configuration, I downloaded the .Cif file of Beta silicon nitride from crystallography.net and also I built it using the space group and then I replicated it to obtain a thin layer ( ending in the same results for both cases ). For stress, I used virial and for strain, it is engineering strain. I attached my files ( Si3N4. in as my initial configuration and Input.in as my input command SiN as the parameters of tersoff potential). I also, attach the diagram I expect to get based on a published paper [1]. But, anyway the answer I get is not correct as I obtain a high value of fracture stress and even strain. I will deeply appreciate your help within any comment. Honestly, this is the problem that I’m working on it for a month. But, unfortunately I couldn’t solve it and I really think that to the best of my knowledge I’m doing the simulation correctly.

Eagerly looking forward to hear back from you,

Kind regards,

Ali

[1] http://pubs.acs.org/doi/abs/10.1021/jz4007977

Stress - Strain.PNG

Stress - Strain ( Paper ).PNG

Input files.rar (48 KB)

you seem to be deforming in z direction, yet your system is extremely shallow in z. i would suggest to check, if your result is dependent on the thickness of your system in z.

axel.

You could check structural properties (density, bond length, angle) of the equilibrated system before tensile simulation to make sure Tersoff is working well in your case.

Sanjib