Abstract: In free electron band model of three different crystal structures,face-centered cubic (fcc),body-centered cubic (bcc),and hexagonal close-packed (hcp) structures,we fine that the average energy of the four lowest band eigenvalues and the five sub-low band eigenvalues (called as average bond energy Em) is rather close to Fermi level EF.Meanwhile,we also confirm that this conclusion still holds for the practical band in some metals,such as Ti,Zr and Hf with hcp structure as well as Fe with bcc structure etc.,using ab initio pseudopotential and average bond energy methods.Thereby one can further understand the physical connotation of average bond energy Em.

Keywords: 
• average bond energy /
• Firmi level /
• band structure