Electronic basis of the hcp, omega and bcc phases in group IVB elements under pressure or on alloying

Using the first principles DFT calculations, we have elucidated the electronic basis of the α→ω and the ω→β transitions in group IVB elements. After considering several possible factors that could give rise to the structural stability of a particular crystal structure, the changes in the band structure energy due to Peierls–Jahn–Teller distortion and crystal-field effects on sub orbital of d bands coupled with Ewald energy differences have been identified as the causes for these transitions. The role of van Hove singularities and consequent electronic topological transitions has also been examined.