Polarity inversion in the electron density of BP crystal

A rigorous analysis of the electron density of the BP crystal in the light of the atoms in molecules theory reveals very unusual properties. The standard polarity ${\mathrm{B}}^{{\delta }_{+}}{\mathrm{P}}^{{\delta }_{-}}$ found at the zinc-blende equilibrium geometry suffers a reversal under the application of hydrostatic pressure. The inversion occurs through an intermediate situation in which the P valence shell is transferred to a non-nuclear maximum before being caught by the B atom.