If you are enrolled at a university as a doctoral student in Potsdam or Berlin, or if you have a work contract that is subject to social insurance obligations, or if you have something like a visiting scholar contract at the University of Potsdam, then you yourself are legally insured against accidents on the way to and from, and at, your workplace.
You can financially hedge against the financial effects of permanent physical damage due to an accident in private circumstances by taking out private accident insurance. Accidents are typically viewed as causing permanent damage if the condition is expected to last longer than three years.
Private accident insurance should therefore cover the loss in salary caused by the accident, the cost of renovating your home and car, household help, and therapies not covered by your health insurance company. If you are in a position to cover these costs yourself, then you do not need private accident insurance.