Regarding C- Si Morse Potential Global/Cutoff

Dear LAMMPS Experts


indentation of Si substrate with diamond indenter, using the Morse potential for C – Si interaction. The parameters are obtained from reference publications as D0 =0.435 eV, α = 4.6487 Å-1 and r0 = 1.9475 Å.


Not able to find cutoff or global cutoff in reference


If not using the optional cutoff, the global cutoff is used which have a significant effect on force output. Can anyone suggest/advice on the global cutoff for C-Si Morse potential

LAMMPS Version: LAMMPS 64-bit 16Mar2018

if you cannot find a cutoff (it probably is listed somewhere, perhaps not quite obvious), you need to make a test to see how much your results depend on the choice of cutoff. a reasonable choice for atomic scale systems would likely be between 10 \AA (somewhat aggressive) and 15\AA (somewhat careful).

any specific reason why you don’t use a Tersoff pair style? that would seem to be more commonly used for these kinds of systems.


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Dear Alex

Thanks for the reply,

Will look for the cutoff in references comprehensively, Indeed I am using a cutoff value of 12. Even small change of 1 A in cutoff has reasonable effect on normal force in test run. Thus looking for reference a value.

The reference publications suggested, Tersoff pair style for Si-Si and C-C, but Morse for C-Si. Will consider your suggestions. Thank You.