Rules for affiliation for student doing unpaid research in his/her free time? Lets say an undergraduate student does some research in his/her free time and wants to write a paper about the findings. What are the rules regarding affiliation when the student tries to publish?


The student is required to include the university as affiliation, because he/she is enrolled in a program at the university
The student is not allowed to include the university as affiliation, because he/she is not officially hired/approved to do research under the name of the university
There are no rules, the student can choose
...?


I guess for graduate students / postdocs / professors it is mandatory to include the university as affiliation, as they get paid by the university to do the research they are doing!?
I don't think there are any "official rules".  (I can't even find a clause in my employment contract that officially requires me to list my university on my papers.)

But as long as you are a student, it's a good idea to list your university as an affiliation.  Even if the university isn't paying you, you do benefit indirectly from the intellectual environment and resources that the university provides: professors, fellow students, library, internet, health insurance, nearby coffee shops, and so on.  It costs you nothing to be generous.  Also, for better or worse, readers will take your paper more seriously.