Effects of in-plane stiffness and charge transfer on thermal expansion of monolayer transition metal dichalcogenide*
Wang Zhan-Yua),b), Zhou Yan-Lic), Wang Xue-Qingb), Wang Feia),b), Sun Qianga),b), Guo Zheng-Xiaoa),b),d), Jia Yua),b)†
       
Calculated mode Grüneisen parameters for monolayers of (a) Mo X 2 and (b) W X 2. In panels (a) and (b), the mode Grüneisen parameters as a function of frequency are presented in the first row, and these values along high-symmetry directions are in the second row. All the mode Grüneisen parameters of the optical phonons are shown without graph legend.