Rashba spin splitting in symmetric structures

It is widely believed that Rasba spin splitting occurs only in systems lacking space inversion invariance. In this letter we present analytical analysis which suggests that non-zero Rashba spin splitting occurs in systems possessing space inversion invariance. We present numerical simulations which confirm that non-zero Rashba spin splitting occurs in symmetric structures but this splitting is several orders of magnitude smaller than the Rashba spin splitting due to broken space inversion invariance.