Giant temperature dependence of the Mott gap size in 1T-TaS 2 : a molecular dynamics study

Li Cheng, Shunhong Zhang, Shuang Qiao, Lizhao Liu, Zheng Liu

Published 2019-08-13Version 1

The lattice thermodynamics of 1T-TaS 2 , e.g. the spontaneous formation of periodic distortion and vibrations around the equilibrium position, is calculated by ab initio molecular dynamics. Based on that, the finite-temperature electronic structure is examined within the Born-Oppenheimer approximation. We show that the Mott gap shrinks by half when the temperature raises from 0 K to 200 K. The gap size reduction is one order of magnitude larger than the temperature variation in energy. This giant temperature dependence arises from the interplay between the electronic correlation and electron-phonon coupling, and is expected to strongly affect the spin interactions.