Help:why the transmission spectrum is negative value？

[qingfang]

Help:I finished the caculation of the transmission spectrum about the carbon nanotube,but the output file displays some negative values.I want to know why.
Generally the data of transmission spectrum is always positive value.
I will appreciate for your help!

[Nordland]

Is it negative like almost zero, but negative?

[qingfang]

It will be obtained very big negative values from this picture T(E)-E.why?

[nori]

It may be due to the issue of Krylov algorithm.
It is expected that using recursion algorithm alternatively will avoid this issue.

[Nordland]

It would be a great help, if you could provide the script for setting up this calculation, so I can try to track it down.
If you do not want to share it on the forum, you can just send it directly to QuantumWise.