Recently we have shown that the structure of the neutron star crust is likely more complicated than suspected so far in literature [9]. We have shown that the quantum corrections to the ground state energy in neutron matter (which could be termed as well either shell correction energy or Casimir energy) at sub-nuclear densities, where various types of inhomogeneities (bubbles, rods, plates) are comparable to the energy differences between various types of inhomogeneous phases. In Ref. [10] the bottom part of the neutron star crust was investigated using the Skyrme-Hartree-Fock approach with the Coulomb interaction treated beyond the Wigner-Seitz approximation. As we have predicted earlier, a variety of nuclear phases is found to coexist in this region. Their stability and relative energies are governed by the Coulomb, surface and shell energies. We have also found that a substantial contribution is coming from the spin-orbit interaction.
Presently we are finalizing a related study concerning the effects on the structure of this so called pasta phase due to the dynamics of various inhomogeneities [11].