Additive maps preserving rank-1 matrices from the space of real symmetric matrices to the space of complex Hermitian matrices

Let S_n(R) be the space of n×n (n≥2) symmetric matrices over the real number field, and let H_n(C) be the space of n×n Hermitian matrices over the complex number field C. Struction of additive maps preserving rank-1 matrices from S_n(C) to H_n(C) are characterized.