questions about the inelastic electron spectroscopy

[Huang Baihan]

Dear Quantumwise staff,
         Recently,   i have been studying the inelastic electron transmission spectrum (IETS) for two probe molecule system, and i have follow the example in ATKTutorials
https://docs.quantumwise.com/tutorials/inelastic_electron_spectrometry_au_h2_au/inelastic_electron_spectrometry_au_h2_au.html
In XLOE, the current formula is give by I(V,T)
=
\sum_{\lambda}
\Big[
\mathcal{I}^{sym}_{\lambda}(V,T)
\mathcal{T}^{sym}_{\lambda}(\epsilon_F)
+
\mathcal{I}^{asym}_{\lambda}(V,T)
\mathcal{T}^{asym}_{\lambda}(\epsilon_F)
\Big], the current  are divided into symmetric and asymmetric contribution ,  and i am puzzed about  the symmetric and asymmetric transmission function formula , first in Inelastic Transmission  Spectrum analyzer , it divided into positive and negative inelastic transmission again, so should I add them  up , dose it mean in the current formula Tsym? second , i found the data are all real number , but in the formula it should have imaginary number in symmetric transmission part. The last question is about the dimension of the current formula, as you can see , the symmetric and asymmetric inelastic transmission function part  depend on the number of phonons and energy, but the symmetric and asymmetric universal functions depend on the bias , number of phonons and temperature ; so i wonder where is the energy dimension go ?
So, I really need your help and  help me solve the puzzlement!
thanks a lot !

[Petr Khomyakov]

Please read the theory papers (see, the first 2 references in the tutorial) for better understanding of what these formulas mean. In the second of the 2 papers, a simple model is also considered, which allows for analytical derivation of the transmission terms.   

[Huang Baihan]

Dear Petr ,
Thanks for your kind reply, i will read the reference listed in the tutorial carefully,

Best regards!
Baihan