What is the true value of bulk band gap of lithium tetraborate single crystal?

Substantial variances in the bulk band gap of lithium tetraborate single crystal determined from numerous theoretical calculations as well as from experimental measurements give rise to the problem what is the true value of Eg for that crystal. In this review, we analyze in detail all available theoretical and experimental data regarding the bulk band gap published by different authors and suggest that the experimental value of = (7.5 ± 0.3) eV determined from the optical absorption edge is the most appropriate value. This is in good agreement with Eg = 7.5 eV calculated via modified linear combination of atomic orbitals (LCAO) method.