Is it appropriate for a candidate to negotiate the salary during the interview?

This is a tricky question and depends upon the level at which you are being assessed. In case of entry level there is hardly any need for it as pay scales are more or less fixed. an exception can be for a really brilliant candidate with a number of options. He/She can then negotiate.

However for an experienced candidate who is looking for a better job as compared to his/her previous one, you should negotiate quoting your past achievements, experience & qualifications. Moreover, you can highlight how you will be an asset to the company.

 Yes if the interviewer opened the discussing for this issue

Yes and inhibitor

In this discussion can be personal knowledge of the potential employee

And wishes

I agreed with all colleagues above, However it is better not to discuss till they inform you

should be that in next interview or if employer inform him about salary rank 

for managers &  Professionals  and for not  time wasting I think it will be good

_______________________________________