Asking something about TAD

Dear All,

Recently, I have read some literatures about the TAD and NEB, I have a lot of questions about the TAD technology. I hope you can give me some suggestions. Thank you very much!
First, I think the difference between TAD and NEB is that NEB give just one final state, yet TAD generates a serial “fianl” states(Please forgive me that I use the word “final”, maybe it is not the real end), that is to say, NEB is just a technology that unrelated with time, while TAD is depend on the simulation time, and every different “final” states is just one coorsponding time point. For example, in the example tab, there are five “final” states and each “final” state coorsponding different time

I didn't follow what your 1st question is. To learn about TAD
generally, you should read some of Art Voter's papers.

Your 2nd Q:

The second is about the method of temperature control in the example tad,
before TAD, we use "fix nve+langevin", while we change that into "fix nvt"
during the TAD, I don't know what's the meaming of this change?

They are both thermostats. See the doc pages for the 2 commands.
Either could be used.