This doesn’t matter. In Tersoff potential files a trio (A B C) means the bonding of B—A—C, which in many cases (e.g., Si Si C) have BA or AC bond lengths beyond the cutoff for the compound it parameterized for (SiC in this case). Therefore it doesn’t matter if parameters like A, B, lambda, etc are zeros or not, since Si-Si-C bonds do not exist. For your own potential file you need to determine if such bonds exist or not, but just make them non-zeros to be on the safe side.

Hi Ray,

Thank you for the response. Just for the sake of clarity, if you check BNC.tersoff for ( C B B ) which I attached here, lambda2 of it should be the mean of ( B B B ) and ( C C C ) according to my understanding. For ( B B B ) it is 2.0774982, and for ( C C C ) it is 2.2119 and Surprisingly for ( C B B ) it has been entered as 2.2054 which doesn’t follow that mean rule. Am I wrong, or there is an explanation ? I really appreciate your help.

Regards,

Ali

BNC.tersoff (5.56 KB)

By asking this question I am sure you have not read the paper by Cagin et. al… Please do so and you shall find the answer.

But I still have question on the method. Generally we only have data for example for ( Si Si Si ) and ( N N N ). How should I fill out for the rest. I mean for ( N Si Si) what should be R and D ?

Thanks,

Ali

You have to find a paper that provides parameters for the Si-N system and cannot just glue two sets of parameters into one.