Toxic former PI trying to block me from presenting work after I quit my PhD I was a PhD student and forced to quit as my PI doubted the new work I did and this PI did not mention any constructive feedback or comments. I signed a resignation letter. Then, I submitted my work to a conference and it was accepted to be published, despite the fact that this the supervisor did not help me at all in any step of this proposed methodology that I proved. 

The PI found out that I am going to present my work and threatened that (s)he is going to block me from the research field unless I put their name on my work, even though I resigned and they doubt the work. It is clear that (s)he is very appreciated in the field and no lab could accept me if (s)he blocks me. (S)he suggested that I will it does not help me to present my work alone.  

Another question is from where does one get the money to attend a conference without the support of a supervisor. I am really shattered and see this as clear bullying and retaliation. By the way, this PI has forced another student who also did great work and published in top tier conferences and journals to leave after four years of hard work.

I don't know what to do. This is work that I did on my own, and he has not the right to be co-author.
Don't be panic. 

If everything you said is true, your PI does not deserve to be a co-author, and I would suggest you not to put his/her name in your poster.


  It is clear that (s)he is very appreciated in the field and no lab
  could accept me if (s)he blocks me.


This is not true.

As you already resigned, the worst they can do to you is not writing a letter of reference. Nothing else.

Just think about it, would they ask/email other research groups "Hey, I just want to check if you-never-heard-of Monica is applying to your group, (s)he is very bad blah blah"? If that really happens, it is them to be questioned.

Note that they do not gain anything by badmouthing you. People can question their ability to select students. And if this behaviour is consistent with different students, they will make a bad reputation for themselves.



Updated:

From @CaptainEmacs:


  Sorry, but this is not realising how blacklisting works. If the PI is
  indeed that powerful, they can do a lot of damage. While OP tries to
  continue in the field, the PI can basically make a side dismissive
  comment or explain how difficult a person OP was or - outright false -
  statements about what OP did, including making underhanded claims
  about sabotage or thefts, out of knowledge of OP. The best chance for
  OP is to switch fields where PI doesn't have a reach or name or go to
  some other big shot who is not influenced by PI and try to convince
  them about their qualities, but this is hard.


I've never heard of such things. Do you have a source for it? or is this a rumor that you hear?

"Powerful" in academia just means that somebody does a lot of good research, and has a lot of collaborations. It doesn't mean they can affect the decision of anybody outside their department.

And if somebody is trying to tell me about their bad former student, the first questions come to mind will be: why this guy needs to spend so much effort going after a random student? why does he think I will care? why can't he just move on?