Hi all, bear with me… this may get confusing.

In the Tersoff potential for alloys, the bond order term requires the calculation of the cutoff function using the i-k parameters and separation (of question here is interactions like this: i-j-k = Si-Si-C). However, the way the potential input file is written, the values for the cutoffs (R and D) provided should be the i-j ones, and there is no separate value for the i-k set (and the code doesn’t seem to hunt these down in the parameter file.

The provided files seem to just use the same cutoff for the Si-Si-C type interaction as would be used for Si-C-Si - but this doesn’t seem to hold based on the way that Tersoff wrote the formulation. The Si-Si cutoff values are 2.85 +/- .15 and the Si-C cutoff is 2.36 +/- .15 - so I would figure this could lead to some differences when the structure begins to deform a fair bit. In my past simulations I had been using the 2.85 value in the Si-Si-C interactions. Curious if anyone knows if this makes a big difference in behavior - or if it may be worth adding in the extra cutoff parameters to the parameter file line?

Thanks,

Dave

David E. Farrell

Graduate Student

Mechanical Engineering

Northwestern University

email: [email protected]…435…