In the framework of a continuum theory, it is shown that the direct
flexoelectric response of a finite sample essentially depends on the surface
polarization energy, even in the thermodynamic limit where the body size tends
to infinity. It is found that a modification of the surface energy can lead to
a change of the polarization response by a factor of two. The origin of the
effect is an electric field produced by surface dipoles induced by the strain
gradient. The unexpected sensitivity of the polarization response to the
surface energy in the thermodynamic limit is conditioned by the fact that the
moments of the surface dipoles may scale as the body size
