Hu Kai, Chen Qin-Jun, Xie Sheng-Yi
School of Physics and Electronics, Hunan University, Changsha 410082, People's Republic of China.
J Phys Condens Matter. 2020 Feb 20;32(8):085402. doi: 10.1088/1361-648X/ab5495. Epub 2019 Nov 5.
By crystal structure prediction and first-principles calculations, we researched the structure transformation and electronic states for a typical transition metal dichalcogenides (TMDs): 1T-TaS under hydrostatic pressure. The layered 1T-TaS will first transform to an 8-fold monoclinic C2/m phase and then to a 10-fold coordinated tetragonal I4/mmm phase which has 3D covalent bond network linked in space. Our calculations suggest that the lone pair electrons of S in 1T-TaS, which keep the stablity of the layered structure, will be activated by pressure and participate the chemical bonding with Ta, to form the high-pressure C2/m and I4/mmm phases. Additionally, collective electronic states of superconductivity also retains in the I4/mmm phase and the critical transition temperature of superconductivity is 9 K at 100 GPa.
通过晶体结构预测和第一性原理计算，我们研究了典型的过渡金属二硫属化物（TMDs）——1T-TaS在静水压力下的结构转变和电子态。层状的1T-TaS首先会转变为八重单斜C2/m相，然后转变为具有三维空间共价键网络连接的十重配位四方I4/mmm相。我们的计算表明，1T-TaS中保持层状结构稳定性的S的孤对电子会被压力激活，并与Ta参与化学键合，形成高压C2/m相和I4/mmm相。此外，超导的集体电子态在I4/mmm相中也得以保留，在100 GPa时超导临界转变温度为9 K。
