Preformed excitonic liquid route to a charge density wave in 2H-TaSe${}_2$

Recent experiments on 2H-TaSe${}_2$ contradict the long-held view of the charge density wave arising from a nested band structure. An intrinsically strong coupling view, involving a charge density wave state arising as a Bose condensation of preformed excitons emerges as an attractive, albeit scantily investigated alternative. Using local density approximation plus multiorbital dynamic mean-field theory, we show that this scenario agrees with a variety of normal state data for 2H-TaSe${}_2$. Based thereupon, the ordered states in a subset of dichalcogenides should be viewed as instabilities of a correlated, preformed excitonic liquid.