具有在位势和力常数交错的一维双原子链晶格振动色散关系

Dispersion Relations of One-dimension Diatomic Chain with On-site Potential and Force Constant Crosses

在简谐近似下,求解了具有在位势和力常数交错的一维双原子链晶格振动的运动学方程.分析了在位势和力常数交错对晶格振动链声学支和光学支的影响.发现了在位势的存在使晶格链产生能隙,并且随在位势的增大,晶格振动频谱发生移动;当在一定的条件下,可使该晶格不存在声学模;交错力常数之比也能提升晶格振动频谱,尤其是对光学支的影响更为显著.

Using the harmonic approximation method, the motion equation of one-dimension diatomic chain with on- site potential and force constant cross is solved and the influences of on - site potential and force constant cross on its dispersion relation are discussed. It has showed that the on - site potential induces the energy gap of one - dimension diatomic chain. When on - site potential increases, the lattice vibration spectra are shifted. No acoustic branches are allowed in the one - dimension diatomie chain under given conditions. The force constant cross is contributed to the shift of the lattice vibration spectra, especially for optical branches.