We investigate the algebraic structure of complex Lie groups equipped with
left-invariant metrics which are expanding semi-algebraic solitons to the
Hermitian curvature flow (HCF). We show that the Lie algebras of such Lie
groups decompose in the semidirect product of a reductive Lie subalgebra with
their nilradicals. Furthermore, we give a structural result concerning
expanding semi-algebraic solitons on complex Lie groups. It turns out that the
restriction of the soliton metric to the nilradical is also an expanding
algebraic soliton and we explain how to construct expanding solitons on complex
Lie groups starting from expanding solitons on their nilradicals.Comment: 14 pages; section 4 extended; last version, to appear in Differential
Geometry and its Application