Question about extracting force constants

[JXGGG-feige]

Dear TDEP developers,

I have a question regarding the extract_forceconstants command. What is the difference between using

extract_forceconstants -rc2 7 -rc4 5

and

extract_forceconstants -rc2 7 -rc3 6 -rc4 5

Specifically, is it acceptable to omit the -rc3 option and directly extract the fourth-order force constants using the first command? Will the absence of -rc3 affect the accuracy or the way TDEP handles the third-order interactions internally?

Thank you very much for your help!