I want an inverted breve that spans the width of two symbols rather than one. I have tried the suggestions in: inverted breve accent in math mode , and in How to put \smallsmile or \smallfrown on top ...
I need to typeset (from bottom up) math bold L with above-dot and widetilde (both centered horizontally above the L), i.e. approximate time-derivative of tensor-valued function. (I would google more, ...