Electronic topological transitions in Zn under compression

The electronic structure of hcp Zn under pressure up to 10 GPa has been calculated self-consistently by means of the scalar relativistic tight-binding linear muffin-tin orbital method. The calculations show that three electronic topological transitions (ETT's) occur in Zn when the $c/a$ axial ratio diminishes under compression. One transition occurs at c/a1.82 when the ``needles'' appear around the symmetry point K of the Brillouin zone. The other two transitions occur at c/a√3, when the ``butterfly'' and ``cigar'' appear simultaneously both around the L point. It has been shown that these ETT's are responsible for a number of anomalies observed in Zn at compression.