How to set the value of GAUS_SIGMA?

[Yongxiancheng]

Thanks for your great code, and I'd like to ask a question.
During the calculation of Electrical conductivity, I found that the value of GAUS_SIGMA determined the value of Electrical conductivity, but there is no illustration of how to set the Gauss value. Would it be possible to detalily explain the computation procedure of the GAUS_SIGMA?
Thank you for your consideration and time again.