I've combined with non-diacritics with diacritics since F.T.(1) was catalogued as both. However, there are other Frédéric Thomases out there, including some writing on similar sounding topics like agriculture, so please don't assign future works based purely on the diacritics.
1) Thomas, Frédéric, 1970-, Parasitism and Ecosystems
2) There appears to be a Frederic Thomas, Inc. publishing books for Chick-Fil-A.