Electron density fluctuations and phase transition in $\alpha$-titanium

It is shown that the topological features of the electronic structure of $\alpha$-titanium lead to the appearance of temperature-induced fluctuations of the electron density, which disappear near the temperature of the phase transition from the HCP ($\alpha$-phase) to the BCC ($\beta$-phase). The experimen-tally observed linear temperature increase in the magnetic susceptibility in the beta-phase and its jump during the transition to the $\beta$-phase are described. The considered fluctuation pattern de-scribes a sharp decrease in the electron entropy and softening of the longitudinal phonon modes associated with the electron-ion interaction. It is shown that the temperature of the phase transition in $\alpha$-titanium depends on the position of the Fermi level, which can be changed by introducing impurities.